CMS PAPER CFT-09-010
CMS Paper
arXiv:0911.4045v2 [physics.ins-det] 5 Jan 2010
2009/12/29
Performance Study of the CMS Barrel Resistive Plate
Chambers with Cosmic Rays
The CMS Collaboration∗
Abstract
In October and November 2008, the CMS collaboration conducted a programme of
cosmic ray data taking, which has recorded about 270 million events. The Resistive
Plate Chamber system, which is part of the CMS muon detection system, was successfully operated in the full barrel. More than 98 % of the channels were operational
during the exercise with typical detection efficiency of 90 %. In this paper, the performance of the detector during these dedicated runs is reported.
∗ See
Appendix A for the list of collaboration members
1
1 Introduction
The primary goal of the Compact Muon Solenoid (CMS) experiment [1] is to explore particle physics at the TeV energy scale exploiting the collisions between protons delivered by the
Large Hadron Collider (LHC) [2]. The Resistive Plate Chamber (RPC) system [3] is part of the
muon detection system and is used for triggering purposes. RPCs have been chosen because of
their good time resolution (about 2 ns) and high granularity, which permit a fast and efficient
triggering of muons over large areas.
During October-November 2008, the CMS Collaboration conducted a month-long data-taking
exercise known as the Cosmic Run At Four Tesla (CRAFT), with the goal of commissioning the
experiment for extended operation [4]. With all installed detector systems participating, CMS
recorded 270 million cosmic-ray-triggered events with the solenoid at a central flux density of
3.8 T.
The muon system is composed of a central barrel (in the pseudo-rapidity window |η | < 1.04)
and two closing endcaps (1.04 < |η | < 2.4). The RPCs participated in the CRAFT data taking
with the full barrel and half of the endcaps in operation. Part of the endcaps was not operational
because the readout electronics was not yet available.
For the RPC system, the CRAFT 2008 exercise has permitted the check of the full data taking
chain, from the detector up to the data acquisition boards, and the confirmation of the detector performance established during the quality control phase [5], also in presence of the CMS
magnetic field. The exercise was also a useful benchmark to complete the commissioning of
the endcap part of the RPC system.
This paper is focused on the barrel RPC system performance. Sections 2 and 3 describe the RPC
system layout, and the operation and monitoring procedures during the CRAFT exercise, respectively. In Section 4, the readout electronics is presented and the synchronization procedure
is described. Section 5 deals with the barrel RPC performance, in terms of cluster size, position
resolution and detection efficiency.
2 RPC system layout
The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter. The silicon pixel and strip tracker, the crystal electromagnetic calorimeter (ECAL) and the
brass-scintillator hadronic calorimeter (HCAL) are located within the solenoidal field volume.
Muons are measured in gas ionization detectors embedded in the steel return yoke. CMS uses
a right-handed coordinate system, with the origin at the nominal collision point, the x-axis
pointing to the centre of the LHC, the y-axis pointing up (perpendicular to the LHC plane),
and the z-axis along the anticlockwise-beam direction. The polar angle, θ, is measured from
the positive z-axis, the azimuthal angle, φ, is measured in the x-y plane.
The RPC detectors are employed in CMS as a dedicated trigger system in both the barrel and
in the endcap regions. They complement the muon tracking system: drift tubes (DT) [6] in the
barrel and cathode strip chambers (CSC) [7] in the endcaps.
From the geometrical point of view, the muon system is divided into five wheels in the barrel
and three disks in each endcap. Each barrel wheel is divided in 12 sectors, covering the full
azimuthal dimension (see Fig. 1). Each sector consists of four layers of DTs and six layers of
RPCs, with a total of 480 RPC stations of average area of 12 m2 . The two innermost DT layers
are sandwiched between RPC layers (RB1in and RB1out for the innermost DT layer, RB2in and
2
2
RPC system layout
RB2out for the second one). The third and fourth DT layers are complemented with a single
RPC layer, placed on their inner side (RB3 and RB4). A detailed description of the muon system
geometry can be found in Ref. [1].
Figure 1: Transverse view of the muon system layout in the barrel region, showing the positions
of the DT and RPC stations.
Each barrel RPC station is mechanically composed of two or three adjacent RPC units, called
“rolls”, making a total of 1020 rolls for the barrel RPC system. Figure 2 shows a schematic
layout of a RPC station composed by two rolls. The CMS RPC rolls are double RPC units,
where each unit is composed of two bakelite electrodes, each 2 mm thick, and a 2 mm wide gas
gap. Readout strips, which are oriented along the beam direction, are placed between the two
RPC units, with an independent electronic channel for each strip. The total readout system of
the barrel RPC detector consists of 68 136 channels.
The strip location defines a point in the local reference frame of the RPC with a precision given
by the strip width, ranging from 2.3 cm, for the innermost RB1in layer, to 4.1 cm, for the RB4
layer (see Table 1). The strip signals are discriminated and shaped into 100 ns digital pulses by
front-end boards with programmable discriminator thresholds.
The RPC detectors, which work in saturated avalanche mode, use a three-component, nonflammable gas mixture composed of 96.2 % C2 H2 F4 (R134a), 3.5 % isobutane (C4 H10 ) and 0.3 %
SF6 . Water vapour is added to obtain a mixture with a relative humidity of 40–50 %, in order
to maintain a constant bakelite resistivity and, thus, avoid a degradation of RPC performance
under high background conditions. The large volume of the total RPC system (18 m3 ) and the
use of a rather expensive gas mixture impose the use of a gas recirculation system. This system
consists of the following modules: the primary supply, the mixer, the humidifier, the closedloop circulators, the gas distributors to the chambers, the purifiers, and the pump. The purifier
3
Figure 2: Schematic layout of a RPC station composed of two rolls.
system is made of a set of filters designed to remove contaminants from the gas mixture. The
system operates with a fraction of fresh gas mixture in the range from 10 % to 2 %. This is the
first time that such a large RPC system is operated with a closed loop gas system.
3 Detector operation and monitoring
The effective working voltage, Veff , relevant for the charge avalanche production inside the
RPC, depends on environmental parameters such as gas temperature (T) and pressure (P),
according to Eq. 1 [8]
Veff = V ×
P0
T
×
P
T0
,
(1)
where Veff is the effective voltage, V is the applied power voltage, and P0 = 1010 mbar and
T0 = 293 K are the reference pressure and temperature, respectively. Only the effective voltage
is relevant when comparing detector performance in different sites and run conditions.
The CMS RPCs have been extensively tested at the production sites and their physics performance was studied [3, 5]. During 2006, a small fraction of the RPC system was calibrated and
operated [9]. In both cases, it was found that 95 % of the maximum plateau efficiency is reached
at an effective voltage of 9.6 kV, corresponding to an average applied voltage of 9.2 kV for the
pressure conditions in the CMS cavern.
For the CRAFT 2008 exercise, the operating voltage was set to 9.2 kV and the electronic thresholds of the readout system were set to 230 mV, corresponding to an induced charge of 180 fC.
These operating conditions are conservative and do not permit the detector to reach its maximum efficiency. This approach was chosen to maintain low noise levels and safe operating
conditions, since this was the first time that the full system was operated. Following extensive
past studies [10], the working conditions were maintained within strict ranges: temperature
lower than 24 ◦ C, humidity in the range 40–50 % and fraction of O2 below 300 ppm.
These parameters were monitored and controlled by the Detector Control System (DCS) [11].
Their values were stored in a database and used, offline, to study the system stability.
4
3.1
3
Detector operation and monitoring
Temperature
Entries
40
35
310
Mean
21.72
RMS
0.701
30
CMS 2008
25
temperature [°C]
# of chambers/ 0.2 °C
Out of the 480 RPC stations, 310 are equipped with a temperature probe installed inside the
mechanical frame. Figure 3 shows in the left plot the temperature distribution of those barrel
stations at the end of the CRAFT period (averaged over one day) and on the right plot its
average vs. time. The system temperature was maintained below 24 ◦ C during the full CRAFT
period, in order to guarantee proper RPC operation. Clear variations are observed when the
electronics of CMS is switched on or off. The steep increase seen at the start of the CRAFT
exercise, when all the detectors were fully operating, is a consequence of the non optimized
cooling of the system. A special effort was dedicated to increase the cooling circuit capability
after the end of the CRAFT exercise. The temperature of the input cooling water has been
reduced by one degree in order to guarantee a constant stable temperature lower than 24 ◦ C,
as confirmed in 2009, during long cosmic rays data taking periods.
30
28
24
20
22
15
20
10
18
5
0
15
CMS 2008
26
16
16
17
18
19
20
21
22
23
24
25
temperature [°C]
16.10.08
23.10.08
30.10.08
06.11.08
date
Figure 3: RPC temperature, as measured by the probes installed inside the stations. Left side:
distribution of RPC temperature taken at the end of the CRAFT period and averaged over one
full day of data taking. Right side: Average RPC temperature as a function of time. Each point
represents the temperature averaged over 4 hours and over all barrel stations. The increase and
the variations of the temperature are triggered by the start of the CMS electronics.
3.2
Currents
The currents drawn by the RPCs, I, are strongly affected by variations of the environmental
conditions. A sudden current increase could also indicate a malfunctioning of the detector.
Therefore, a careful and continuous monitoring of the currents is performed. Each RPC station
is powered by a separate high voltage supply. The current drawn in each RPC station is read
out and stored through the DCS. Figure 4 shows in the left plot the I distribution at an operating voltage of 9.2 kV, for the 480 barrel stations, at the end of the CRAFT period. Only for
11 stations the value of I is larger than 3 µA. During the CRAFT exercise, ten units out of 2040
were disconnected because of problems with the high voltage connections, leaving the corresponding rolls working in single gap mode. Figure 4 right plot shows that the average current
drawn by the stations was around 1 µA and stable in time. No correlation is observed between
the mean current values and the temperature variations, in the operating range.
3.3
Counting rates
The RPC noise rate is carefully monitored, since abnormal values in some parts of the detector
can result in high fake muon trigger rates. At the beginning of each run, dedicated calibration
data were taken and analysed to identify and mask noisy readout channels with rates above
5
Entries
90
80
480
Mean
0.9323
RMS
0.9803
70
60
50
current [µA]
# of chambers/ 0.2 µA
3.4 Gas monitoring
3
2.5
CMS 2008
2
1.5
CMS 2008
40
1
30
20
0.5
10
0
0
1
2
3
4
5
6
7
8
9
10
current [µA]
0
16.10.08
23.10.08
30.10.08
06.11.08
date
Figure 4: Distribution of the current drawn by the RPCs. Left plot shows the average over one
full day of data taking at the end of the CRAFT period. The plot has no overflow. Right plot:
average current as a function of time. Each point is the average current over 4 hours and over
all barrel stations. The operating voltage is 9.2 kV.
100 Hz/cm2 . This value was chosen because it corresponds to the limit that the trigger system
can sustain. The total number of masked and dead channels was stable during the CRAFT
period, at about 1 % of the total number of channels in both cases.
The average noise per second and per cm2 is computed for each roll by adding the contributions
from all non-masked channels. The distribution of the number of rolls as a function of the
average noise is shown in Fig. 5, for one specific run. Only 3 % of the rolls have an average
noise rate greater than 1 Hz/cm2 .
Although the average noise rate is very low, a problem related to events with correlated noise
on several layers has been detected few times per day affecting about 10−3 of the total data
taking time during the CRAFT exercise. A special effort has been made to understand the
sensitivity of the RPCs to external noise sources. The detector grounding has been improved
where possible, and further studies are in progress. Preliminary analyses have demonstrated
that the fake trigger rate is reduced by two orders of magnitude when the LHC trigger algorithm is used instead of the dedicated cosmic ray trigger employed during the CRAFT exercise.
The LHC trigger algorithm requires more stringent constraints on the incoming muon direction
and is less sensitive to the detector noise.
3.4
Gas monitoring
The mixture composition and its quality are monitored by two independent devices. The Gas
Quality Monitor [12, 13] performs chemical analyses (mainly gas chromatography, pH and fluoride monitoring). The Gas Gain Monitor [14], is based on the monitoring of the performance
of three sets of 50 × 50 cm2 single gap RPCs, each supplied with a different gas mixture (fresh
gas, and gas from the recirculating system, before and after the purifiers).
During the CRAFT exercise, the gas system was operated continuously with a fraction of 8 %
of fresh mix. The lifetime of the purifiers before regeneration was about 36 hours between
regenerations of first stage purifier, to remove water from gas mixture humidity, and one week
between regenerations of second stage purifier, to remove air contamination. The full system
was running smoothly during the operation. The downtime due to gas system stops was less
than 1 %.
6
number of rolls/0.01 Hz/cm2
4
Entries
Mean
RMS
102
Synchronization of RPC data
1020
0.72
5
CMS 2008
10
1
10-2
10-1
1
102
10
noise rate (Hz/cm2)
Figure 5: Example distribution of the number of rolls as a function of the average noise in
the roll, for a given data taking run. Channels exceeding 100 Hz/cm2 are masked and do not
contribute to the average noise. The operating voltage is 9.2 kV.
4 Synchronization of RPC data
Muon signals detected by the RPC chambers and transmitted by the readout electronics must
arrive in dedicated electronic boards at a specified time, in order to correctly contribute to the
trigger decisions. In addition, RPC data sent to the CMS Data Acquisition system (DAQ) and
RPC trigger information must be associated to the right LHC bunch crossing (BX: 25 ns time
interval).
The different steps of data transmission in the RPC system are described in detail in Ref. [15].
After pulse discrimination in the front end boards, the data are transmitted asynchronously to
the Link Boards situated on the CMS detector, where zero-suppression is performed. The data
are then sent through optical fibres to the CMS counting room, in the underground cavern,
where RPC muon trigger objects are identified, as part of the CMS Level-1 trigger system, and
sent to the Global Muon Trigger. In parallel, the data are sent to the CMS DAQ system. To
ensure integration with CMS, the RPC readout and trigger systems work in synchronous mode
using the CMS Timing, Trigger and Control (TTC) system [16].
The TTC signals (including clock and reference bunch crossing identification) are distributed to
the Link Boards, where the signals from the detector are synchronized with the LHC clock. The
data are assigned to the proper bunch crossing according to a time window determined by the
length of the TTC fibres, the muon time of flight, and the signal propagation and transmission
times along the strips, cables and electronics.
The RPC readout [17] is designed to send data from up to 8 consecutive bunch crossings (BXs)
to the DAQ system: the trigger BX plus 3 pre- and 4 post-trigger BXs. During the CRAFT
exercise, only 7 BXs were transmitted to the DAQ (±3 BXs around the triggered event).
The timing setups of the system are different for the LHC beam mode and for the cosmic ray
7
runs. In beam mode the synchronization is driven by beam collisions, which are fixed in phase
with respect to the LHC clock, while in the cosmic mode this phase is arbitrary: cosmic rays
arrive randomly with respect to the LHC clock. The synchronizations of the upper and lower
parts of the detector differ significantly in the two modes, due to the asymmetric phi distribution of the cosmic rays.
In order to optimize the data synchronization, initial delays were estimated, based on the length
of cables and fibres. The bottom-central part of the detector was chosen as a reference, and delays of data from other parts of the detector were fine-tuned to optimize the data alignment
in time. The same timing was kept for the full CRAFT period. As an illustration of the RPC
synchronization during the CRAFT exercise, Fig. 6 presents a typical example of the time distribution of the data coming from individual RPCs. The time is counted with respect to the
bunch crossing assigned by the RPC Level-1 global trigger logic, based on the coincidence of
at least 3 chambers along a muon trajectory. The peak in the central bin corresponds to data
which are synchronous with the RPC Level-1 trigger. The spread to the two neighbouring bins
is caused mainly by the arbitrary choice of the synchronization phase, relevant only for cosmic
ray runs. The spread over the other bins is due to the non-perfect synchronization of contributing triggers, and to a background caused by Link Boards connected to the most noisy electronic
channels.
×10
entries
3
450
Cosmic data
400
Contribution from most noisy channels
350
300
CMS 2008
250
200
150
100
50
0
-3
-2
-1
0
1
2
3
bunch crossing (25 ns units)
Figure 6: Typical time distribution (in bunch crossing units of 25 ns) of the data coming from
individual RPCs with respect to the RPC global trigger time. The dashed line shows the background caused by the 10 over 1020 Link Boards connected to the most noisy channels.
In view of the good quality of the present data, much better synchronization is expected for
LHC runs.
5 Detector performance
The performance of the RPC system has been studied by making use of the local DT hit reconstruction [6]. The three innermost DT layers are able to locally reconstruct three dimensional
muon track segments with up to eight hits in the rφ plane and up to four hits in the rz plane.
8
5
Detector performance
The outermost DT layer provides a segment in the rφ plane.
The extrapolation of a DT track segment onto an RPC plane allows the study of the local RPC
performance, by searching for RPC channels over threshold in a small region around the impact
point. Previous studies [9] have shown that a range of ± 2 strips between the extrapolated
impact point and the closest firing strip is adequate.
In addition, the CRAFT exercise led to the identification of 15 swapped readout cables out of a
total of 4720, and a few cases of RPC to DT misalignments at the level of more than 1 cm.
In the following sub-sections the results on cluster size, position resolution and detection efficiency are reported for the whole barrel system. The RPC cluster size and the position resolution are studied separately for layers with different strip pitches. No special selection is applied
to the DT track segments used for the extrapolation, except for the requirement that no other
segment is reconstructed in the DT station. This condition is imposed to reject multiple muon
events and other possible ambiguous topologies. Moreover, only pointing segments in the rφ
plane have been used in these analyses. A pointing track segment in the rφ plane is defined as
a segment within an angle of ± 20 degrees around the normal to the RPC layer, in the plane
perpendicular to the strip direction. All the figures have been produced by analysing a run of
about 2 million events, representative of the full CRAFT period.
5.1
Cluster size
A cluster is defined as a consecutive set of strips, each of them collecting an induced charge
above the discrimination threshold of 180 fC. The number of strips in the cluster is called the
cluster size.
The cluster size depends on the RPC strip pitch, on the impact point position with respect to
the strip, and on the track crossing angle. Figure 7 shows the cluster size distribution for the
RB1in layers, for pointing muons. The different strip pitches and the average cluster sizes are
given for all layers in Table 1. The fractions of events having cluster sizes corresponding to 1,
2, 3 or more than 3 strips are shown for different layers in Fig. 8.
Table 1: Strip pitch and average cluster size, counted as the number of strips, for pointing track
segments, with operating voltage of 9.2 kV.
RPC layer strip pitch (cm) average cluster size
RB1in
2.3
1.52
RB1out
2.5
1.46
RB2in
2.8
1.41
RB2out
3.0
1.38
RB3
3.5
1.31
RB4
4.1
1.25
The number of firing strips for a crossing muon is a function of the local impact point position
with respect to the RPC strip. The distribution in Fig. 9 shows the deviation, ∆, measured in
strip pitch units, between the impact point and the cluster centre for the RB1in layer, in a local
reference frame. In this local frame the fired strip is between 0 and 1 for events with cluster
size of 1, the two fired strips are between −1 and 1 for events with cluster size of 2, and the
three fired strips are between −1 and 2 for events with cluster size of 3. The three distributions,
normalized to the same area, are overlayed. Events with cluster size of 1 are more frequent for
tracks crossing the RPC layer close to the middle of a strip, while the fraction of events with a
cluster size of 2 increases for muons close to the edge between two adjacent strips.
9
fraction
5.1 Cluster size
Entries 3319060
0.6
Mean
1.52
RMS
0.843
0.5
CMS 2008
0.4
0.3
0.2
0.1
0
1
2
3
4
5
6
7
8 9 10
cluster size
fraction
Figure 7: Normalized distribution of the cluster size for the RB1in layer, for pointing track
segments.
cluster size 1
cluster size 2
cluster size 3
cluster size >3
1
0.8
CMS 2008
0.6
0.4
0.2
0
RB1
in
(2.3
RB1
RB2
RB2
RB4
RB3
(4.1
(3.5
ou (
in (2.
8 cm out (3.0 c
cm)
cm)
cm) t 2.5 cm
m
)
)
)
RPC layer
Figure 8: Relative population of reconstructed clusters with size equal to 1, 2, 3 and more than
3 strips, for each RPC layer.
10
5
Detector performance
In addition, the cluster size depends on the muon incident angle with respect to the RPC surface, in the plane orthogonal to the strip direction. This is visible in Fig. 10, which presents the
dependence of the average cluster size on the absolute value of the tangent of the angle α, defined as the angle between the muon direction and the normal to the RPC surface in the plane
perpendicular to the strip direction, for the RB1in layer. This dependence is due both to the
increased path length in the crossed gas gap and to the RPC double gap structure where two
independent avalanches develop in the two gas gaps, 6 mm apart, which may induce signals
on different strips, increasing the cluster size.
arbitrary units
It should be noted that, because of the bending of muon trajectories due to the magnetic field,
low momentum muons coming from the interaction point, during LHC runs, may cross the
RPC detectors with relatively large angles. Cosmic muons are very useful to study these topologies since they cross the detector at all possible angles, depending on the sector.
cluster size 1
cluster size 2
cluster size 3
0.025
CMS 2008
CMS
2008
0.02
0.015
0.01
0.005
0
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
3
segment impact point (strip pitch)
strip cluster size 1
strips cluster size 2
strips cluster size 3
Figure 9: Distribution of the track impact point for the RB1in layer in a local reference frame,
for events with cluster size of 1, 2 and 3, in units of strip pitch. The local frame, described by
the drawing under the plot, is defined in such a way that the fired strip is between 0 and 1 for
events with cluster size of 1, the two fired strips are between −1 and 1 for events with cluster
size of 2, and the three fired strips are between −1 and 2 for events with cluster size of 3. The
three distributions are normalized to the same unit area.
5.2
Position resolution
The centre of a cluster provides a measurement of the position of the muon track crossing point,
in the rφ plane. In order to study the RPC position resolution, the cluster centre is compared
to the extrapolated point of the DT segment onto the RPC layer. The distribution of the off-set
between the position of the track crossing point onto the surface separating the two gaps and
the cluster centre, named residual, is computed for every roll, providing an estimate of the
relative DT and RPC alignment.
11
average cluster size
5.3 Detection efficiency
2.8
2.6
CMS 2008
2.4
2.2
2
1.8
1.6
1.4
0
1
2
3
4
5
|tan α |
Figure 10: Average cluster size as a function of the absolute value of the tangent of the angle α,
defined as the angle between the track direction and the normal to the RPC surface in the plane
perpendicular to the strip direction, for the RB1in layer and with an operating voltage of 9.2 kV.
Figure 11 presents the distribution of the mean value of the residuals for all barrel rolls. The
relative alignment is of a few millimetres, but two cases of a few centimetres have also been observed (not visible on the plot scale). The mean values extracted from the residual distributions
have been used to correct the data offline, in order to improve the position resolution.
Figure 12 shows the residual distribution in cm for the RB1in layer, after having applied the
alignment corrections, for events with cluster size lower than four.
The analysis of the RPC residuals has been performed for all layers, corresponding to different
strip pitches as reported in Table 1, and for events with different cluster sizes. The RMS values
of the residual distribution are presented in Fig. 13, as a function of the layer, for different
cluster sizes. The trend reflects the variation of the strip pitch and the geometry of the different
RPC layers.
5.3
Detection efficiency
The most important parameter defining the RPC performance is the detection efficiency. The
DT segment extrapolation, presented at the beginning of Section 5, is used to estimate the RPC
efficiency, for a full roll.
For each DT track segment extrapolated onto the RPC surface, a roll is considered efficient if
at least one RPC strip is over threshold within ± 2 strips from the extrapolated impact point.
Figure 14 shows the efficiency vs. the local impact point on the RPC surface. The pattern due to
the spacers placed on a 10 × 10 cm2 grid is clearly visible. Moreover, a reduction of the overall
efficiency is visible in the y coordinate (as defined in the figure) at about 55 cm, where only one
gap is present.
The roll efficiency distribution is shown in Fig. 15 for a typical run, taken at the operating volt-
12
number of rolls/0.1 cm
5
Entries
200
Detector performance
1020
Mean
-0.0039
RMS
0.21
CMS 2008
150
100
50
0
-1
-0.8 -0.6 -0.4 -0.2
0
0.2
0.4
0.6
0.8
1
residual mean value (cm)
fraction/0.25 cm
Figure 11: Normalized distribution of the mean value of the residuals in cm, for all the RPC
rolls. Two entries are out of the range.
Entries 3234989
0.09
0.08
Mean
RMS
CMS 2008
-0.007
0.89
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
-10
-8
-6
-4
-2
0
2
4
6
8
10
residual (cm)
Figure 12: Normalized distribution of the residuals in cm, for the RB1in layer (events with
cluster size larger than three are not included).
RMS residuals (cm)
13
2
overall
cluster size 1
cluster size 2
cluster size 3
1.8
1.6
CMS 2008
1.4
1.2
1
0.8
0.6
RB1
in
(2.3
RB2
RB1
RB2
RB4
RB3
(4.1
(3.5
ou (
in (2.
8 cm out (3.0 c
cm)
c
cm) t 2.5 cm
m
m)
)
)
)
RPC layer
Figure 13: RMS of the distributions of the residuals, for the different layers (corresponding to
different strip pitches) and for different cluster sizes.
age of 9.2 kV. The peak of the distribution is about 90 %, while the tail at lower efficiency values
is due to now known swapped cables, chambers working in single gap mode and chambers
with synchronization problems.
After the end of the CRAFT exercise many improvements have been obtained and the operating
conditions have been optimized. In 2009 the efficiency distribution was around 95 % at 9.4 kV.
6 Conclusions
Data collected during the CRAFT 2008 period have been very useful for detector commissioning. About 98 % of the electronic channels were operational during the exercise. Hardware
problems such as swapped cables and electronic failures have been identified and fixed. The
relative position of each RPC station with respect to the DT chambers has been measured in
the rφ direction, and the position resolution of the RPC system has been determined. Software
tools to monitor the system performance have been developed and tuned during the running
period. The performance of the barrel system has been measured from data. The results show
a good stability of the detector and an efficiency around 90 % at the operating voltage of 9.2 kV.
Many improvements have been made after the CRAFT 2008 exercise. The temperature of the
input cooling water has been reduced by one degree. Hardware failures have been fixed, the
working voltage and the electronic threshold have been optimized, and the synchronization
of the RPC barrel signals has been improved. Although more systematic studies are still in
progress, the RPC barrel system is ready for LHC beam collisions.
14
6
Conclusions
y (cm)
y
12 x 24 spacers per roll
every 10 cm
X
X (cm)
Gas gap
Gas gap
Forward roll
Gas gap
Gas gap
Single gap working region
RPC Up
RPC Down
Backward roll
Figure 14: Efficiency of an RB1in roll as a function of the x and y coordinates (as defined in the
figure) of the extrapolated track impact point. The lower efficiency spots are due to the dead
regions induced by spacers on a 10 × 10 cm2 grid. An efficiency reduction is also visible for the
y coordinate at about 55 cm, where only a single gap is present.
Acknowledgements
We thank the technical and administrative staff at CERN and other CMS Institutes, and acknowledge support from: FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ,
and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia);
Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG,
and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India);
IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR
(Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia);
MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK
and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA). Individuals have received
support from the Marie-Curie IEF program (European Union); the Leventis Foundation; the A.
P. Sloan Foundation; and the Alexander von Humboldt Foundation.
number of rolls
15
250
200
Entries
CMS 2008
1020
Mean
86.29
RMS
14.61
150
100
50
0
10 20 30 40 50 60 70 80 90 100
efficiency (%)
Figure 15: Efficiency distribution for barrel rolls, at an operating voltage of 9.2 kV. The tail at
lower efficiency values is due to now known swapped cables, chambers working in single gap
mode and chambers with synchronization problems.
References
[1] CMS Collaboration, “The CMS experiment at the CERN LHC”, JINST 3 (2008) S08004.
doi:10.1088/1748-0221/3/08/S08004.
[2] L. Evans and P. Bryant (eds.), “LHC machine”, JINST 3 (2008) S08001.
doi:10.1088/1748-0221/3/08/S08001.
[3] M. Abbrescia et al., “Cosmic ray tests of double-gap resistive plate chambers for the CMS
experiment”, Nucl. Instrum. Meth. A550 (2005) 116–126.
doi:10.1016/j.nima.2005.06.074.
[4] CMS Collaboration, “The CMS Cosmic Run at Four Tesla”, submitted to JINST (2009).
[5] M. Abbrescia et al., “Production and quality control of the barrel RPC chambers of the
CMS experiment”, Nucl. Phys. Proc. Suppl. 150 (2006) 290–294.
doi:10.1016/j.nuclphysbps.2004.11.389.
[6] CMS Collaboration, “Results On Local Muon Reconstruction in DT Chambers From
Analysis of Cosmic Muon Data”, submitted to JINST (2009).
[7] CMS Collaboration, “CSC performance”, submitted to JINST (2009).
[8] M. Abbrescia et al., “Resistive plate chambers performances at cosmic rays fluxes”, Nucl.
Instrum. Meth. A359 (1995) 603–609. doi:10.1016/0168-9002(94)01698-4.
[9] A. Colaleo et al., “First measurements of the performance of the barrel RPC system in
CMS”, Nucl. Instrum. Meth. A609 (2009) 114–121.
doi:10.1016/j.nima.2009.07.099.
16
6
Conclusions
[10] M. Abbrescia et al., “Long term performance of double gap resistive plate chambers
under gamma irradiation”, Nucl. Instrum. Meth. A477 (2002) 293–298.
doi:10.1016/S0168-9002(01)01860-5.
[11] P. Paolucci and G. Polese, “The Detector Control Systems for the CMS Resistive Plate
Chamber”, CMS NOTE 2008/036 (2008).
[12] M. Abbrescia et al., “The gas monitoring system for the resistive plate chamber detector
of the CMS experiment at LHC”, Nucl. Phys. Proc. Suppl. 177-178 (2008) 293–296.
doi:10.1016/j.nuclphysbps.2007.11.133.
[13] M. Abbrescia et al., “HF production in CMS-Resistive Plate Chambers”, Nucl. Phys. Proc.
Suppl. 158 (2006) 30–34. doi:10.1016/j.nuclphysbps.2006.07.002.
[14] L. Benussi et al., “The CMS RPC gas gain monitoring system: an overview and
preliminary results”, Nucl. Instrum. Meth. A602 (2009) 805–808, arXiv:0812.1108.
doi:10.1016/j.nima.2008.12.175.
[15] K. Bunkowski et al., “Synchronization methods for the PAC RPC trigger system in the
CMS experiment”, Measur. Sci. Tech. 18 (2007) 2446–2455.
doi:10.1088/0957-0233/18/8/020.
[16] CMS Trigger/DAQ Group, “CMS L1 Trigger Control system”, CMS NOTE 2002/033
(2002).
[17] W. M. Zabolotny et al., “Implementation of the data acquisition system for the resistive
plate chamber pattern comparator muon trigger in the CMS experiment”, Measur. Sci.
Tech. 18 (2007) 2456–2464. doi:10.1088/0957-0233/18/8/021.
17
A
The CMS Collaboration
Yerevan Physics Institute, Yerevan, Armenia
S. Chatrchyan, V. Khachatryan, A.M. Sirunyan
Institut für Hochenergiephysik der OeAW, Wien, Austria
W. Adam, B. Arnold, H. Bergauer, T. Bergauer, M. Dragicevic, M. Eichberger, J. Erö, M. Friedl,
R. Frühwirth, V.M. Ghete, J. Hammer1 , S. Hänsel, M. Hoch, N. Hörmann, J. Hrubec, M. Jeitler,
G. Kasieczka, K. Kastner, M. Krammer, D. Liko, I. Magrans de Abril, I. Mikulec, F. Mittermayr,
B. Neuherz, M. Oberegger, M. Padrta, M. Pernicka, H. Rohringer, S. Schmid, R. Schöfbeck,
T. Schreiner, R. Stark, H. Steininger, J. Strauss, A. Taurok, F. Teischinger, T. Themel, D. Uhl,
P. Wagner, W. Waltenberger, G. Walzel, E. Widl, C.-E. Wulz
National Centre for Particle and High Energy Physics, Minsk, Belarus
V. Chekhovsky, O. Dvornikov, I. Emeliantchik, A. Litomin, V. Makarenko, I. Marfin,
V. Mossolov, N. Shumeiko, A. Solin, R. Stefanovitch, J. Suarez Gonzalez, A. Tikhonov
Research Institute for Nuclear Problems, Minsk, Belarus
A. Fedorov, A. Karneyeu, M. Korzhik, V. Panov, R. Zuyeuski
Research Institute of Applied Physical Problems, Minsk, Belarus
P. Kuchinsky
Universiteit Antwerpen, Antwerpen, Belgium
W. Beaumont, L. Benucci, M. Cardaci, E.A. De Wolf, E. Delmeire, D. Druzhkin, M. Hashemi,
X. Janssen, T. Maes, L. Mucibello, S. Ochesanu, R. Rougny, M. Selvaggi, H. Van Haevermaet,
P. Van Mechelen, N. Van Remortel
Vrije Universiteit Brussel, Brussel, Belgium
V. Adler, S. Beauceron, S. Blyweert, J. D’Hondt, S. De Weirdt, O. Devroede, J. Heyninck, A. Kalogeropoulos, J. Maes, M. Maes, M.U. Mozer, S. Tavernier, W. Van Doninck1 , P. Van Mulders,
I. Villella
Université Libre de Bruxelles, Bruxelles, Belgium
O. Bouhali, E.C. Chabert, O. Charaf, B. Clerbaux, G. De Lentdecker, V. Dero, S. Elgammal,
A.P.R. Gay, G.H. Hammad, P.E. Marage, S. Rugovac, C. Vander Velde, P. Vanlaer, J. Wickens
Ghent University, Ghent, Belgium
M. Grunewald, B. Klein, A. Marinov, D. Ryckbosch, F. Thyssen, M. Tytgat, L. Vanelderen,
P. Verwilligen
Université Catholique de Louvain, Louvain-la-Neuve, Belgium
S. Basegmez, G. Bruno, J. Caudron, C. Delaere, P. Demin, D. Favart, A. Giammanco,
G. Grégoire, V. Lemaitre, O. Militaru, S. Ovyn, K. Piotrzkowski1 , L. Quertenmont, N. Schul
Université de Mons, Mons, Belgium
N. Beliy, E. Daubie
Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil
G.A. Alves, M.E. Pol, M.H.G. Souza
Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
W. Carvalho, D. De Jesus Damiao, C. De Oliveira Martins, S. Fonseca De Souza, L. Mundim,
V. Oguri, A. Santoro, S.M. Silva Do Amaral, A. Sznajder
Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, Brazil
18
A The CMS Collaboration
T.R. Fernandez Perez Tomei, M.A. Ferreira Dias, E. M. Gregores2 , S.F. Novaes
Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria
K. Abadjiev1 , T. Anguelov, J. Damgov, N. Darmenov1 , L. Dimitrov, V. Genchev1 , P. Iaydjiev,
S. Piperov, S. Stoykova, G. Sultanov, R. Trayanov, I. Vankov
University of Sofia, Sofia, Bulgaria
A. Dimitrov, M. Dyulendarova, V. Kozhuharov, L. Litov, E. Marinova, M. Mateev, B. Pavlov,
P. Petkov, Z. Toteva1
Institute of High Energy Physics, Beijing, China
G.M. Chen, H.S. Chen, W. Guan, C.H. Jiang, D. Liang, B. Liu, X. Meng, J. Tao, J. Wang, Z. Wang,
Z. Xue, Z. Zhang
State Key Lab. of Nucl. Phys. and Tech., Peking University, Beijing, China
Y. Ban, J. Cai, Y. Ge, S. Guo, Z. Hu, Y. Mao, S.J. Qian, H. Teng, B. Zhu
Universidad de Los Andes, Bogota, Colombia
C. Avila, M. Baquero Ruiz, C.A. Carrillo Montoya, A. Gomez, B. Gomez Moreno, A.A. Ocampo
Rios, A.F. Osorio Oliveros, D. Reyes Romero, J.C. Sanabria
Technical University of Split, Split, Croatia
N. Godinovic, K. Lelas, R. Plestina, D. Polic, I. Puljak
University of Split, Split, Croatia
Z. Antunovic, M. Dzelalija
Institute Rudjer Boskovic, Zagreb, Croatia
V. Brigljevic, S. Duric, K. Kadija, S. Morovic
University of Cyprus, Nicosia, Cyprus
R. Fereos, M. Galanti, J. Mousa, A. Papadakis, F. Ptochos, P.A. Razis, D. Tsiakkouri, Z. Zinonos
National Institute of Chemical Physics and Biophysics, Tallinn, Estonia
A. Hektor, M. Kadastik, K. Kannike, M. Müntel, M. Raidal, L. Rebane
Helsinki Institute of Physics, Helsinki, Finland
E. Anttila, S. Czellar, J. Härkönen, A. Heikkinen, V. Karimäki, R. Kinnunen, J. Klem, M.J. Kortelainen, T. Lampén, K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, T. Mäenpää, J. Nysten,
E. Tuominen, J. Tuominiemi, D. Ungaro, L. Wendland
Lappeenranta University of Technology, Lappeenranta, Finland
K. Banzuzi, A. Korpela, T. Tuuva
Laboratoire d’Annecy-le-Vieux de Physique des Particules, IN2P3-CNRS, Annecy-le-Vieux,
France
P. Nedelec, D. Sillou
DSM/IRFU, CEA/Saclay, Gif-sur-Yvette, France
M. Besancon, R. Chipaux, M. Dejardin, D. Denegri, J. Descamps, B. Fabbro, J.L. Faure, F. Ferri,
S. Ganjour, F.X. Gentit, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, M.C. Lemaire,
E. Locci, J. Malcles, M. Marionneau, L. Millischer, J. Rander, A. Rosowsky, D. Rousseau,
M. Titov, P. Verrecchia
Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France
S. Baffioni, L. Bianchini, M. Bluj3 , P. Busson, C. Charlot, L. Dobrzynski, R. Granier de Cassagnac, M. Haguenauer, P. Miné, P. Paganini, Y. Sirois, C. Thiebaux, A. Zabi
19
Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de Haute
Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France
J.-L. Agram4 , A. Besson, D. Bloch, D. Bodin, J.-M. Brom, E. Conte4 , F. Drouhin4 , J.-C. Fontaine4 ,
D. Gelé, U. Goerlach, L. Gross, P. Juillot, A.-C. Le Bihan, Y. Patois, J. Speck, P. Van Hove
Université de Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique
Nucléaire de Lyon, Villeurbanne, France
C. Baty, M. Bedjidian, J. Blaha, G. Boudoul, H. Brun, N. Chanon, R. Chierici, D. Contardo,
P. Depasse, T. Dupasquier, H. El Mamouni, F. Fassi5 , J. Fay, S. Gascon, B. Ille, T. Kurca, T. Le
Grand, M. Lethuillier, N. Lumb, L. Mirabito, S. Perries, M. Vander Donckt, P. Verdier
E. Andronikashvili Institute of Physics, Academy of Science, Tbilisi, Georgia
N. Djaoshvili, N. Roinishvili, V. Roinishvili
Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi,
Georgia
N. Amaglobeli
RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany
R. Adolphi, G. Anagnostou, R. Brauer, W. Braunschweig, M. Edelhoff, H. Esser, L. Feld,
W. Karpinski, A. Khomich, K. Klein, N. Mohr, A. Ostaptchouk, D. Pandoulas, G. Pierschel,
F. Raupach, S. Schael, A. Schultz von Dratzig, G. Schwering, D. Sprenger, M. Thomas, M. Weber,
B. Wittmer, M. Wlochal
RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany
O. Actis, G. Altenhöfer, W. Bender, P. Biallass, M. Erdmann, G. Fetchenhauer1 , J. Frangenheim,
T. Hebbeker, G. Hilgers, A. Hinzmann, K. Hoepfner, C. Hof, M. Kirsch, T. Klimkovich,
P. Kreuzer1 , D. Lanske† , M. Merschmeyer, A. Meyer, B. Philipps, H. Pieta, H. Reithler,
S.A. Schmitz, L. Sonnenschein, M. Sowa, J. Steggemann, H. Szczesny, D. Teyssier, C. Zeidler
RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany
M. Bontenackels, M. Davids, M. Duda, G. Flügge, H. Geenen, M. Giffels, W. Haj Ahmad, T. Hermanns, D. Heydhausen, S. Kalinin, T. Kress, A. Linn, A. Nowack, L. Perchalla, M. Poettgens,
O. Pooth, P. Sauerland, A. Stahl, D. Tornier, M.H. Zoeller
Deutsches Elektronen-Synchrotron, Hamburg, Germany
M. Aldaya Martin, U. Behrens, K. Borras, A. Campbell, E. Castro, D. Dammann, G. Eckerlin,
A. Flossdorf, G. Flucke, A. Geiser, D. Hatton, J. Hauk, H. Jung, M. Kasemann, I. Katkov,
C. Kleinwort, H. Kluge, A. Knutsson, E. Kuznetsova, W. Lange, W. Lohmann, R. Mankel1 ,
M. Marienfeld, A.B. Meyer, S. Miglioranzi, J. Mnich, M. Ohlerich, J. Olzem, A. Parenti,
C. Rosemann, R. Schmidt, T. Schoerner-Sadenius, D. Volyanskyy, C. Wissing, W.D. Zeuner1
University of Hamburg, Hamburg, Germany
C. Autermann, F. Bechtel, J. Draeger, D. Eckstein, U. Gebbert, K. Kaschube, G. Kaussen,
R. Klanner, B. Mura, S. Naumann-Emme, F. Nowak, U. Pein, C. Sander, P. Schleper, T. Schum,
H. Stadie, G. Steinbrück, J. Thomsen, R. Wolf
Institut für Experimentelle Kernphysik, Karlsruhe, Germany
J. Bauer, P. Blüm, V. Buege, A. Cakir, T. Chwalek, W. De Boer, A. Dierlamm, G. Dirkes,
M. Feindt, U. Felzmann, M. Frey, A. Furgeri, J. Gruschke, C. Hackstein, F. Hartmann1 ,
S. Heier, M. Heinrich, H. Held, D. Hirschbuehl, K.H. Hoffmann, S. Honc, C. Jung, T. Kuhr,
T. Liamsuwan, D. Martschei, S. Mueller, Th. Müller, M.B. Neuland, M. Niegel, O. Oberst,
A. Oehler, J. Ott, T. Peiffer, D. Piparo, G. Quast, K. Rabbertz, F. Ratnikov, N. Ratnikova, M. Renz,
C. Saout1 , G. Sartisohn, A. Scheurer, P. Schieferdecker, F.-P. Schilling, G. Schott, H.J. Simonis,
20
A The CMS Collaboration
F.M. Stober, P. Sturm, D. Troendle, A. Trunov, W. Wagner, J. Wagner-Kuhr, M. Zeise, V. Zhukov6 ,
E.B. Ziebarth
Institute of Nuclear Physics ”Demokritos”, Aghia Paraskevi, Greece
G. Daskalakis, T. Geralis, K. Karafasoulis, A. Kyriakis, D. Loukas, A. Markou, C. Markou,
C. Mavrommatis, E. Petrakou, A. Zachariadou
University of Athens, Athens, Greece
L. Gouskos, P. Katsas, A. Panagiotou1
University of Ioánnina, Ioánnina, Greece
I. Evangelou, P. Kokkas, N. Manthos, I. Papadopoulos, V. Patras, F.A. Triantis
KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary
G. Bencze1 , L. Boldizsar, G. Debreczeni, C. Hajdu1 , S. Hernath, P. Hidas, D. Horvath7 , K. Krajczar, A. Laszlo, G. Patay, F. Sikler, N. Toth, G. Vesztergombi
Institute of Nuclear Research ATOMKI, Debrecen, Hungary
N. Beni, G. Christian, J. Imrek, J. Molnar, D. Novak, J. Palinkas, G. Szekely, Z. Szillasi1 ,
K. Tokesi, V. Veszpremi
University of Debrecen, Debrecen, Hungary
A. Kapusi, G. Marian, P. Raics, Z. Szabo, Z.L. Trocsanyi, B. Ujvari, G. Zilizi
Panjab University, Chandigarh, India
S. Bansal, H.S. Bawa, S.B. Beri, V. Bhatnagar, M. Jindal, M. Kaur, R. Kaur, J.M. Kohli,
M.Z. Mehta, N. Nishu, L.K. Saini, A. Sharma, A. Singh, J.B. Singh, S.P. Singh
University of Delhi, Delhi, India
S. Ahuja, S. Arora, S. Bhattacharya8 , S. Chauhan, B.C. Choudhary, P. Gupta, S. Jain, S. Jain,
M. Jha, A. Kumar, K. Ranjan, R.K. Shivpuri, A.K. Srivastava
Bhabha Atomic Research Centre, Mumbai, India
R.K. Choudhury, D. Dutta, S. Kailas, S.K. Kataria, A.K. Mohanty, L.M. Pant, P. Shukla, A. Topkar
Tata Institute of Fundamental Research - EHEP, Mumbai, India
T. Aziz, M. Guchait9 , A. Gurtu, M. Maity10 , D. Majumder, G. Majumder, K. Mazumdar,
A. Nayak, A. Saha, K. Sudhakar
Tata Institute of Fundamental Research - HECR, Mumbai, India
S. Banerjee, S. Dugad, N.K. Mondal
Institute for Studies in Theoretical Physics & Mathematics (IPM), Tehran, Iran
H. Arfaei, H. Bakhshiansohi, A. Fahim, A. Jafari, M. Mohammadi Najafabadi, A. Moshaii,
S. Paktinat Mehdiabadi, S. Rouhani, B. Safarzadeh, M. Zeinali
University College Dublin, Dublin, Ireland
M. Felcini
INFN Sezione di Bari a , Università di Bari b , Politecnico di Bari c , Bari, Italy
M. Abbresciaa,b , L. Barbonea , F. Chiumaruloa , A. Clementea , A. Colaleoa , D. Creanzaa,c ,
G. Cuscelaa , N. De Filippisa , M. De Palmaa,b , G. De Robertisa , G. Donvitoa , F. Fedelea , L. Fiorea ,
M. Francoa , G. Iasellia,c , N. Lacalamitaa , F. Loddoa , L. Lusitoa,b , G. Maggia,c , M. Maggia ,
N. Mannaa,b , B. Marangellia,b , S. Mya,c , S. Natalia,b , S. Nuzzoa,b , G. Papagnia , S. Piccolomoa ,
G.A. Pierroa , C. Pintoa , A. Pompilia,b , G. Pugliesea,c , R. Rajana , A. Ranieria , F. Romanoa,c ,
21
G. Rosellia,b , G. Selvaggia,b , Y. Shindea , L. Silvestrisa , S. Tupputia,b , G. Zitoa
INFN Sezione di Bologna a , Universita di Bologna b , Bologna, Italy
G. Abbiendia , W. Bacchia,b , A.C. Benvenutia , M. Boldinia , D. Bonacorsia , S. BraibantGiacomellia,b , V.D. Cafaroa , S.S. Caiazzaa , P. Capiluppia,b , A. Castroa,b , F.R. Cavalloa ,
G. Codispotia,b , M. Cuffiania,b , I. D’Antonea , G.M. Dallavallea,1 , F. Fabbria , A. Fanfania,b ,
D. Fasanellaa , P. Giacomellia , V. Giordanoa , M. Giuntaa,1 , C. Grandia , M. Guerzonia ,
S. Marcellinia , G. Masettia,b , A. Montanaria , F.L. Navarriaa,b , F. Odoricia , G. Pellegrinia ,
A. Perrottaa , A.M. Rossia,b , T. Rovellia,b , G. Sirolia,b , G. Torromeoa , R. Travaglinia,b
INFN Sezione di Catania a , Universita di Catania b , Catania, Italy
S. Albergoa,b , S. Costaa,b , R. Potenzaa,b , A. Tricomia,b , C. Tuvea
INFN Sezione di Firenze a , Universita di Firenze b , Firenze, Italy
G. Barbaglia , G. Broccoloa,b , V. Ciullia,b , C. Civininia , R. D’Alessandroa,b , E. Focardia,b ,
S. Frosalia,b , E. Galloa , C. Gentaa,b , G. Landia,b , P. Lenzia,b,1 , M. Meschinia , S. Paolettia ,
G. Sguazzonia , A. Tropianoa
INFN Laboratori Nazionali di Frascati, Frascati, Italy
L. Benussi, M. Bertani, S. Bianco, S. Colafranceschi11 , D. Colonna11 , F. Fabbri, M. Giardoni,
L. Passamonti, D. Piccolo, D. Pierluigi, B. Ponzio, A. Russo
INFN Sezione di Genova, Genova, Italy
P. Fabbricatore, R. Musenich
INFN Sezione di Milano-Biccoca a , Universita di Milano-Bicocca b , Milano, Italy
A. Benagliaa , M. Callonia , G.B. Ceratia,b,1 , P. D’Angeloa , F. De Guioa , F.M. Farinaa , A. Ghezzia ,
P. Govonia,b , M. Malbertia,b,1 , S. Malvezzia , A. Martellia , D. Menascea , V. Miccioa,b , L. Moronia ,
P. Negria,b , M. Paganonia,b , D. Pedrinia , A. Pulliaa,b , S. Ragazzia,b , N. Redaellia , S. Salaa ,
R. Salernoa,b , T. Tabarelli de Fatisa,b , V. Tancinia,b , S. Taronia,b
INFN Sezione di Napoli a , Universita di Napoli ”Federico II” b , Napoli, Italy
S. Buontempoa , N. Cavalloa , A. Cimminoa,b,1 , M. De Gruttolaa,b,1 , F. Fabozzia,12 , A.O.M. Iorioa ,
L. Listaa , D. Lomidzea , P. Nolia,b , P. Paoluccia , C. Sciaccaa,b
INFN Sezione di Padova a , Università di Padova b , Padova, Italy
P. Azzia,1 , N. Bacchettaa , L. Barcellana , P. Bellana,b,1 , M. Bellatoa , M. Benettonia , M. Biasottoa,13 ,
D. Biselloa,b , E. Borsatoa,b , A. Brancaa , R. Carlina,b , L. Castellania , P. Checchiaa , E. Contia ,
F. Dal Corsoa , M. De Mattiaa,b , T. Dorigoa , U. Dossellia , F. Fanzagoa , F. Gasparinia,b ,
U. Gasparinia,b , P. Giubilatoa,b , F. Gonellaa , A. Greselea,14 , M. Gulminia,13 , A. Kaminskiya,b ,
S. Lacapraraa,13 , I. Lazzizzeraa,14 , M. Margonia,b , G. Marona,13 , S. Mattiazzoa,b , M. Mazzucatoa ,
M. Meneghellia , A.T. Meneguzzoa,b , M. Michelottoa , F. Montecassianoa , M. Nespoloa ,
M. Passaseoa , M. Pegoraroa , L. Perrozzia , N. Pozzobona,b , P. Ronchesea,b , F. Simonettoa,b ,
N. Tonioloa , E. Torassaa , M. Tosia,b , A. Triossia , S. Vaninia,b , S. Venturaa , P. Zottoa,b ,
G. Zumerlea,b
INFN Sezione di Pavia a , Universita di Pavia b , Pavia, Italy
P. Baessoa,b , U. Berzanoa , S. Bricolaa , M.M. Necchia,b , D. Paganoa,b , S.P. Rattia,b , C. Riccardia,b ,
P. Torrea,b , A. Vicinia , P. Vituloa,b , C. Viviania,b
INFN Sezione di Perugia a , Universita di Perugia b , Perugia, Italy
D. Aisaa , S. Aisaa , E. Babuccia , M. Biasinia,b , G.M. Bileia , B. Caponeria,b , B. Checcuccia , N. Dinua ,
L. Fanòa , L. Farnesinia , P. Laricciaa,b , A. Lucaronia,b , G. Mantovania,b , A. Nappia,b , A. Pilusoa ,
V. Postolachea , A. Santocchiaa,b , L. Servolia , D. Tonoiua , A. Vedaeea , R. Volpea,b
22
A The CMS Collaboration
INFN Sezione di Pisa a , Universita di Pisa b , Scuola Normale Superiore di Pisa c , Pisa, Italy
P. Azzurria,c , G. Bagliesia , J. Bernardinia,b , L. Berrettaa , T. Boccalia , A. Boccia,c , L. Borrelloa,c ,
F. Bosia , F. Calzolaria , R. Castaldia , R. Dell’Orsoa , F. Fioria,b , L. Foàa,c , S. Gennaia,c , A. Giassia ,
A. Kraana , F. Ligabuea,c , T. Lomtadzea , F. Mariania , L. Martinia , M. Massaa , A. Messineoa,b ,
A. Moggia , F. Pallaa , F. Palmonaria , G. Petragnania , G. Petrucciania,c , F. Raffaellia , S. Sarkara ,
G. Segneria , A.T. Serbana , P. Spagnoloa,1 , R. Tenchinia,1 , S. Tolainia , G. Tonellia,b,1 , A. Venturia ,
P.G. Verdinia
INFN Sezione di Roma a , Universita di Roma ”La Sapienza” b , Roma, Italy
S. Baccaroa,15 , L. Baronea,b , A. Bartolonia , F. Cavallaria,1 , I. Dafineia , D. Del Rea,b , E. Di
Marcoa,b , M. Diemoza , D. Francia,b , E. Longoa,b , G. Organtinia,b , A. Palmaa,b , F. Pandolfia,b ,
R. Paramattia,1 , F. Pellegrinoa , S. Rahatloua,b , C. Rovellia
INFN Sezione di Torino a , Università di Torino b , Università del Piemonte Orientale (Novara) c , Torino, Italy
G. Alampia , N. Amapanea,b , R. Arcidiaconoa,b , S. Argiroa,b , M. Arneodoa,c , C. Biinoa ,
M.A. Borgiaa,b , C. Bottaa,b , N. Cartigliaa , R. Castelloa,b , G. Cerminaraa,b , M. Costaa,b ,
D. Dattolaa , G. Dellacasaa , N. Demariaa , G. Dugheraa , F. Dumitrachea , A. Grazianoa,b ,
C. Mariottia , M. Maronea,b , S. Masellia , E. Migliorea,b , G. Milaa,b , V. Monacoa,b , M. Musicha,b ,
M. Nervoa,b , M.M. Obertinoa,c , S. Oggeroa,b , R. Paneroa , N. Pastronea , M. Pelliccionia,b ,
A. Romeroa,b , M. Ruspaa,c , R. Sacchia,b , A. Solanoa,b , A. Staianoa , P.P. Trapania,b,1 , D. Trocinoa,b ,
A. Vilela Pereiraa,b , L. Viscaa,b , A. Zampieria
INFN Sezione di Trieste a , Universita di Trieste b , Trieste, Italy
F. Ambroglinia,b , S. Belfortea , F. Cossuttia , G. Della Riccaa,b , B. Gobboa , A. Penzoa
Kyungpook National University, Daegu, Korea
S. Chang, J. Chung, D.H. Kim, G.N. Kim, D.J. Kong, H. Park, D.C. Son
Wonkwang University, Iksan, Korea
S.Y. Bahk
Chonnam National University, Kwangju, Korea
S. Song
Konkuk University, Seoul, Korea
S.Y. Jung
Korea University, Seoul, Korea
B. Hong, H. Kim, J.H. Kim, K.S. Lee, D.H. Moon, S.K. Park, H.B. Rhee, K.S. Sim
Seoul National University, Seoul, Korea
J. Kim
University of Seoul, Seoul, Korea
M. Choi, G. Hahn, I.C. Park
Sungkyunkwan University, Suwon, Korea
S. Choi, Y. Choi, J. Goh, H. Jeong, T.J. Kim, J. Lee, S. Lee
Vilnius University, Vilnius, Lithuania
M. Janulis, D. Martisiute, P. Petrov, T. Sabonis
Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico
H. Castilla Valdez1 , A. Sánchez Hernández
23
Universidad Iberoamericana, Mexico City, Mexico
S. Carrillo Moreno
Universidad Autónoma de San Luis Potosı́, San Luis Potosı́, Mexico
A. Morelos Pineda
University of Auckland, Auckland, New Zealand
P. Allfrey, R.N.C. Gray, D. Krofcheck
University of Canterbury, Christchurch, New Zealand
N. Bernardino Rodrigues, P.H. Butler, T. Signal, J.C. Williams
National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan
M. Ahmad, I. Ahmed, W. Ahmed, M.I. Asghar, M.I.M. Awan, H.R. Hoorani, I. Hussain,
W.A. Khan, T. Khurshid, S. Muhammad, S. Qazi, H. Shahzad
Institute of Experimental Physics, Warsaw, Poland
M. Cwiok, R. Dabrowski, W. Dominik, K. Doroba, M. Konecki, J. Krolikowski, K. Pozniak16 ,
R. Romaniuk, W. Zabolotny16 , P. Zych
Soltan Institute for Nuclear Studies, Warsaw, Poland
T. Frueboes, R. Gokieli, L. Goscilo, M. Górski, M. Kazana, K. Nawrocki, M. Szleper, G. Wrochna,
P. Zalewski
Laboratório de Instrumentação e Fı́sica Experimental de Partı́culas, Lisboa, Portugal
N. Almeida, L. Antunes Pedro, P. Bargassa, A. David, P. Faccioli, P.G. Ferreira Parracho,
M. Freitas Ferreira, M. Gallinaro, M. Guerra Jordao, P. Martins, G. Mini, P. Musella, J. Pela,
L. Raposo, P.Q. Ribeiro, S. Sampaio, J. Seixas, J. Silva, P. Silva, D. Soares, M. Sousa, J. Varela,
H.K. Wöhri
Joint Institute for Nuclear Research, Dubna, Russia
I. Altsybeev, I. Belotelov, P. Bunin, Y. Ershov, I. Filozova, M. Finger, M. Finger Jr., A. Golunov,
I. Golutvin, N. Gorbounov, V. Kalagin, A. Kamenev, V. Karjavin, V. Konoplyanikov, V. Korenkov, G. Kozlov, A. Kurenkov, A. Lanev, A. Makankin, V.V. Mitsyn, P. Moisenz, E. Nikonov,
D. Oleynik, V. Palichik, V. Perelygin, A. Petrosyan, R. Semenov, S. Shmatov, V. Smirnov,
D. Smolin, E. Tikhonenko, S. Vasil’ev, A. Vishnevskiy, A. Volodko, A. Zarubin, V. Zhiltsov
Petersburg Nuclear Physics Institute, Gatchina (St Petersburg), Russia
N. Bondar, L. Chtchipounov, A. Denisov, Y. Gavrikov, G. Gavrilov, V. Golovtsov, Y. Ivanov,
V. Kim, V. Kozlov, P. Levchenko, G. Obrant, E. Orishchin, A. Petrunin, Y. Shcheglov, A. Shchetkovskiy, V. Sknar, I. Smirnov, V. Sulimov, V. Tarakanov, L. Uvarov, S. Vavilov, G. Velichko,
S. Volkov, A. Vorobyev
Institute for Nuclear Research, Moscow, Russia
Yu. Andreev, A. Anisimov, P. Antipov, A. Dermenev, S. Gninenko, N. Golubev, M. Kirsanov,
N. Krasnikov, V. Matveev, A. Pashenkov, V.E. Postoev, A. Solovey, A. Solovey, A. Toropin,
S. Troitsky
Institute for Theoretical and Experimental Physics, Moscow, Russia
A. Baud, V. Epshteyn, V. Gavrilov, N. Ilina, V. Kaftanov† , V. Kolosov, M. Kossov1 , A. Krokhotin,
S. Kuleshov, A. Oulianov, G. Safronov, S. Semenov, I. Shreyber, V. Stolin, E. Vlasov, A. Zhokin
Moscow State University, Moscow, Russia
E. Boos, M. Dubinin17 , L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, O. Kodolova, I. Lokhtin,
S. Petrushanko, L. Sarycheva, V. Savrin, A. Snigirev, I. Vardanyan
24
A The CMS Collaboration
P.N. Lebedev Physical Institute, Moscow, Russia
I. Dremin, M. Kirakosyan, N. Konovalova, S.V. Rusakov, A. Vinogradov
State Research Center of Russian Federation, Institute for High Energy Physics, Protvino,
Russia
S. Akimenko, A. Artamonov, I. Azhgirey, S. Bitioukov, V. Burtovoy, V. Grishin1 , V. Kachanov,
D. Konstantinov, V. Krychkine, A. Levine, I. Lobov, V. Lukanin, Y. Mel’nik, V. Petrov, R. Ryutin,
S. Slabospitsky, A. Sobol, A. Sytine, L. Tourtchanovitch, S. Troshin, N. Tyurin, A. Uzunian,
A. Volkov
Vinca Institute of Nuclear Sciences, Belgrade, Serbia
P. Adzic, M. Djordjevic, D. Jovanovic18 , D. Krpic18 , D. Maletic, J. Puzovic18 , N. Smiljkovic
Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT),
Madrid, Spain
M. Aguilar-Benitez, J. Alberdi, J. Alcaraz Maestre, P. Arce, J.M. Barcala, C. Battilana, C. Burgos
Lazaro, J. Caballero Bejar, E. Calvo, M. Cardenas Montes, M. Cepeda, M. Cerrada, M. Chamizo
Llatas, F. Clemente, N. Colino, M. Daniel, B. De La Cruz, A. Delgado Peris, C. Diez Pardos,
C. Fernandez Bedoya, J.P. Fernández Ramos, A. Ferrando, J. Flix, M.C. Fouz, P. Garcia-Abia,
A.C. Garcia-Bonilla, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, J. Marin,
G. Merino, J. Molina, A. Molinero, J.J. Navarrete, J.C. Oller, J. Puerta Pelayo, L. Romero,
J. Santaolalla, C. Villanueva Munoz, C. Willmott, C. Yuste
Universidad Autónoma de Madrid, Madrid, Spain
C. Albajar, M. Blanco Otano, J.F. de Trocóniz, A. Garcia Raboso, J.O. Lopez Berengueres
Universidad de Oviedo, Oviedo, Spain
J. Cuevas, J. Fernandez Menendez, I. Gonzalez Caballero, L. Lloret Iglesias, H. Naves Sordo,
J.M. Vizan Garcia
Instituto de Fı́sica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain
I.J. Cabrillo, A. Calderon, S.H. Chuang, I. Diaz Merino, C. Diez Gonzalez, J. Duarte Campderros, M. Fernandez, G. Gomez, J. Gonzalez Sanchez, R. Gonzalez Suarez, C. Jorda, P. Lobelle
Pardo, A. Lopez Virto, J. Marco, R. Marco, C. Martinez Rivero, P. Martinez Ruiz del Arbol,
F. Matorras, T. Rodrigo, A. Ruiz Jimeno, L. Scodellaro, M. Sobron Sanudo, I. Vila, R. Vilar
Cortabitarte
CERN, European Organization for Nuclear Research, Geneva, Switzerland
D. Abbaneo, E. Albert, M. Alidra, S. Ashby, E. Auffray, J. Baechler, P. Baillon, A.H. Ball,
S.L. Bally, D. Barney, F. Beaudette19 , R. Bellan, D. Benedetti, G. Benelli, C. Bernet, P. Bloch,
S. Bolognesi, M. Bona, J. Bos, N. Bourgeois, T. Bourrel, H. Breuker, K. Bunkowski, D. Campi,
T. Camporesi, E. Cano, A. Cattai, J.P. Chatelain, M. Chauvey, T. Christiansen, J.A. Coarasa
Perez, A. Conde Garcia, R. Covarelli, B. Curé, A. De Roeck, V. Delachenal, D. Deyrail, S. Di
Vincenzo20 , S. Dos Santos, T. Dupont, L.M. Edera, A. Elliott-Peisert, M. Eppard, M. Favre,
N. Frank, W. Funk, A. Gaddi, M. Gastal, M. Gateau, H. Gerwig, D. Gigi, K. Gill, D. Giordano,
J.P. Girod, F. Glege, R. Gomez-Reino Garrido, R. Goudard, S. Gowdy, R. Guida, L. Guiducci,
J. Gutleber, M. Hansen, C. Hartl, J. Harvey, B. Hegner, H.F. Hoffmann, A. Holzner, A. Honma,
M. Huhtinen, V. Innocente, P. Janot, G. Le Godec, P. Lecoq, C. Leonidopoulos, R. Loos,
C. Lourenço, A. Lyonnet, A. Macpherson, N. Magini, J.D. Maillefaud, G. Maire, T. Mäki,
L. Malgeri, M. Mannelli, L. Masetti, F. Meijers, P. Meridiani, S. Mersi, E. Meschi, A. Meynet
Cordonnier, R. Moser, M. Mulders, J. Mulon, M. Noy, A. Oh, G. Olesen, A. Onnela, T. Orimoto,
L. Orsini, E. Perez, G. Perinic, J.F. Pernot, P. Petagna, P. Petiot, A. Petrilli, A. Pfeiffer, M. Pierini,
M. Pimiä, R. Pintus, B. Pirollet, H. Postema, A. Racz, S. Ravat, S.B. Rew, J. Rodrigues Antunes,
25
G. Rolandi21 , M. Rovere, V. Ryjov, H. Sakulin, D. Samyn, H. Sauce, C. Schäfer, W.D. Schlatter,
M. Schröder, C. Schwick, A. Sciaba, I. Segoni, A. Sharma, N. Siegrist, P. Siegrist, N. Sinanis,
T. Sobrier, P. Sphicas22 , D. Spiga, M. Spiropulu17 , F. Stöckli, P. Traczyk, P. Tropea, J. Troska,
A. Tsirou, L. Veillet, G.I. Veres, M. Voutilainen, P. Wertelaers, M. Zanetti
Paul Scherrer Institut, Villigen, Switzerland
W. Bertl, K. Deiters, W. Erdmann, K. Gabathuler, R. Horisberger, Q. Ingram, H.C. Kaestli,
S. König, D. Kotlinski, U. Langenegger, F. Meier, D. Renker, T. Rohe, J. Sibille23 ,
A. Starodumov24
Institute for Particle Physics, ETH Zurich, Zurich, Switzerland
B. Betev, L. Caminada25 , Z. Chen, S. Cittolin, D.R. Da Silva Di Calafiori, S. Dambach25 ,
G. Dissertori, M. Dittmar, C. Eggel25 , J. Eugster, G. Faber, K. Freudenreich, C. Grab, A. Hervé,
W. Hintz, P. Lecomte, P.D. Luckey, W. Lustermann, C. Marchica25 , P. Milenovic26 , F. Moortgat, A. Nardulli, F. Nessi-Tedaldi, L. Pape, F. Pauss, T. Punz, A. Rizzi, F.J. Ronga, L. Sala,
A.K. Sanchez, M.-C. Sawley, V. Sordini, B. Stieger, L. Tauscher† , A. Thea, K. Theofilatos,
D. Treille, P. Trüb25 , M. Weber, L. Wehrli, J. Weng, S. Zelepoukine27
Universität Zürich, Zurich, Switzerland
C. Amsler, V. Chiochia, S. De Visscher, C. Regenfus, P. Robmann, T. Rommerskirchen,
A. Schmidt, D. Tsirigkas, L. Wilke
National Central University, Chung-Li, Taiwan
Y.H. Chang, E.A. Chen, W.T. Chen, A. Go, C.M. Kuo, S.W. Li, W. Lin
National Taiwan University (NTU), Taipei, Taiwan
P. Bartalini, P. Chang, Y. Chao, K.F. Chen, W.-S. Hou, Y. Hsiung, Y.J. Lei, S.W. Lin, R.-S. Lu,
J. Schümann, J.G. Shiu, Y.M. Tzeng, K. Ueno, Y. Velikzhanin, C.C. Wang, M. Wang
Cukurova University, Adana, Turkey
A. Adiguzel, A. Ayhan, A. Azman Gokce, M.N. Bakirci, S. Cerci, I. Dumanoglu, E. Eskut,
S. Girgis, E. Gurpinar, I. Hos, T. Karaman, T. Karaman, A. Kayis Topaksu, P. Kurt, G. Önengüt,
G. Önengüt Gökbulut, K. Ozdemir, S. Ozturk, A. Polatöz, K. Sogut28 , B. Tali, H. Topakli,
D. Uzun, L.N. Vergili, M. Vergili
Middle East Technical University, Physics Department, Ankara, Turkey
I.V. Akin, T. Aliev, S. Bilmis, M. Deniz, H. Gamsizkan, A.M. Guler, K. Öcalan, M. Serin, R. Sever,
U.E. Surat, M. Zeyrek
Bogaziçi University, Department of Physics, Istanbul, Turkey
M. Deliomeroglu, D. Demir29 , E. Gülmez, A. Halu, B. Isildak, M. Kaya30 , O. Kaya30 , S. Ozkorucuklu31 , N. Sonmez32
National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine
L. Levchuk, S. Lukyanenko, D. Soroka, S. Zub
University of Bristol, Bristol, United Kingdom
F. Bostock, J.J. Brooke, T.L. Cheng, D. Cussans, R. Frazier, J. Goldstein, N. Grant,
M. Hansen, G.P. Heath, H.F. Heath, C. Hill, B. Huckvale, J. Jackson, C.K. Mackay, S. Metson,
D.M. Newbold33 , K. Nirunpong, V.J. Smith, J. Velthuis, R. Walton
Rutherford Appleton Laboratory, Didcot, United Kingdom
K.W. Bell, C. Brew, R.M. Brown, B. Camanzi, D.J.A. Cockerill, J.A. Coughlan, N.I. Geddes,
K. Harder, S. Harper, B.W. Kennedy, P. Murray, C.H. Shepherd-Themistocleous, I.R. Tomalin,
J.H. Williams† , W.J. Womersley, S.D. Worm
26
A The CMS Collaboration
Imperial College, University of London, London, United Kingdom
R. Bainbridge, G. Ball, J. Ballin, R. Beuselinck, O. Buchmuller, D. Colling, N. Cripps, G. Davies,
M. Della Negra, C. Foudas, J. Fulcher, D. Futyan, G. Hall, J. Hays, G. Iles, G. Karapostoli, B.C. MacEvoy, A.-M. Magnan, J. Marrouche, J. Nash, A. Nikitenko24 , A. Papageorgiou,
M. Pesaresi, K. Petridis, M. Pioppi34 , D.M. Raymond, N. Rompotis, A. Rose, M.J. Ryan,
C. Seez, P. Sharp, G. Sidiropoulos1 , M. Stettler, M. Stoye, M. Takahashi, A. Tapper, C. Timlin,
S. Tourneur, M. Vazquez Acosta, T. Virdee1 , S. Wakefield, D. Wardrope, T. Whyntie, M. Wingham
Brunel University, Uxbridge, United Kingdom
J.E. Cole, I. Goitom, P.R. Hobson, A. Khan, P. Kyberd, D. Leslie, C. Munro, I.D. Reid,
C. Siamitros, R. Taylor, L. Teodorescu, I. Yaselli
Boston University, Boston, USA
T. Bose, M. Carleton, E. Hazen, A.H. Heering, A. Heister, J. St. John, P. Lawson, D. Lazic,
D. Osborne, J. Rohlf, L. Sulak, S. Wu
Brown University, Providence, USA
J. Andrea, A. Avetisyan, S. Bhattacharya, J.P. Chou, D. Cutts, S. Esen, G. Kukartsev, G. Landsberg, M. Narain, D. Nguyen, T. Speer, K.V. Tsang
University of California, Davis, Davis, USA
R. Breedon, M. Calderon De La Barca Sanchez, M. Case, D. Cebra, M. Chertok, J. Conway,
P.T. Cox, J. Dolen, R. Erbacher, E. Friis, W. Ko, A. Kopecky, R. Lander, A. Lister, H. Liu,
S. Maruyama, T. Miceli, M. Nikolic, D. Pellett, J. Robles, M. Searle, J. Smith, M. Squires, J. Stilley,
M. Tripathi, R. Vasquez Sierra, C. Veelken
University of California, Los Angeles, Los Angeles, USA
V. Andreev, K. Arisaka, D. Cline, R. Cousins, S. Erhan1 , J. Hauser, M. Ignatenko, C. Jarvis,
J. Mumford, C. Plager, G. Rakness, P. Schlein† , J. Tucker, V. Valuev, R. Wallny, X. Yang
University of California, Riverside, Riverside, USA
J. Babb, M. Bose, A. Chandra, R. Clare, J.A. Ellison, J.W. Gary, G. Hanson, G.Y. Jeng, S.C. Kao,
F. Liu, H. Liu, A. Luthra, H. Nguyen, G. Pasztor35 , A. Satpathy, B.C. Shen† , R. Stringer, J. Sturdy,
V. Sytnik, R. Wilken, S. Wimpenny
University of California, San Diego, La Jolla, USA
J.G. Branson, E. Dusinberre, D. Evans, F. Golf, R. Kelley, M. Lebourgeois, J. Letts, E. Lipeles,
B. Mangano, J. Muelmenstaedt, M. Norman, S. Padhi, A. Petrucci, H. Pi, M. Pieri, R. Ranieri,
M. Sani, V. Sharma, S. Simon, F. Würthwein, A. Yagil
University of California, Santa Barbara, Santa Barbara, USA
C. Campagnari, M. D’Alfonso, T. Danielson, J. Garberson, J. Incandela, C. Justus, P. Kalavase,
S.A. Koay, D. Kovalskyi, V. Krutelyov, J. Lamb, S. Lowette, V. Pavlunin, F. Rebassoo, J. Ribnik,
J. Richman, R. Rossin, D. Stuart, W. To, J.R. Vlimant, M. Witherell
California Institute of Technology, Pasadena, USA
A. Apresyan, A. Bornheim, J. Bunn, M. Chiorboli, M. Gataullin, D. Kcira, V. Litvine, Y. Ma,
H.B. Newman, C. Rogan, V. Timciuc, J. Veverka, R. Wilkinson, Y. Yang, L. Zhang, K. Zhu,
R.Y. Zhu
Carnegie Mellon University, Pittsburgh, USA
B. Akgun, R. Carroll, T. Ferguson, D.W. Jang, S.Y. Jun, M. Paulini, J. Russ, N. Terentyev,
H. Vogel, I. Vorobiev
27
University of Colorado at Boulder, Boulder, USA
J.P. Cumalat, M.E. Dinardo, B.R. Drell, W.T. Ford, B. Heyburn, E. Luiggi Lopez, U. Nauenberg,
K. Stenson, K. Ulmer, S.R. Wagner, S.L. Zang
Cornell University, Ithaca, USA
L. Agostino, J. Alexander, F. Blekman, D. Cassel, A. Chatterjee, S. Das, L.K. Gibbons, B. Heltsley,
W. Hopkins, A. Khukhunaishvili, B. Kreis, V. Kuznetsov, J.R. Patterson, D. Puigh, A. Ryd, X. Shi,
S. Stroiney, W. Sun, W.D. Teo, J. Thom, J. Vaughan, Y. Weng, P. Wittich
Fairfield University, Fairfield, USA
C.P. Beetz, G. Cirino, C. Sanzeni, D. Winn
Fermi National Accelerator Laboratory, Batavia, USA
S. Abdullin, M.A. Afaq1 , M. Albrow, B. Ananthan, G. Apollinari, M. Atac, W. Badgett, L. Bagby,
J.A. Bakken, B. Baldin, S. Banerjee, K. Banicz, L.A.T. Bauerdick, A. Beretvas, J. Berryhill,
P.C. Bhat, K. Biery, M. Binkley, I. Bloch, F. Borcherding, A.M. Brett, K. Burkett, J.N. Butler,
V. Chetluru, H.W.K. Cheung, F. Chlebana, I. Churin, S. Cihangir, M. Crawford, W. Dagenhart,
M. Demarteau, G. Derylo, D. Dykstra, D.P. Eartly, J.E. Elias, V.D. Elvira, D. Evans, L. Feng,
M. Fischler, I. Fisk, S. Foulkes, J. Freeman, P. Gartung, E. Gottschalk, T. Grassi, D. Green,
Y. Guo, O. Gutsche, A. Hahn, J. Hanlon, R.M. Harris, B. Holzman, J. Howell, D. Hufnagel,
E. James, H. Jensen, M. Johnson, C.D. Jones, U. Joshi, E. Juska, J. Kaiser, B. Klima, S. Kossiakov,
K. Kousouris, S. Kwan, C.M. Lei, P. Limon, J.A. Lopez Perez, S. Los, L. Lueking, G. Lukhanin,
S. Lusin1 , J. Lykken, K. Maeshima, J.M. Marraffino, D. Mason, P. McBride, T. Miao, K. Mishra,
S. Moccia, R. Mommsen, S. Mrenna, A.S. Muhammad, C. Newman-Holmes, C. Noeding,
V. O’Dell, O. Prokofyev, R. Rivera, C.H. Rivetta, A. Ronzhin, P. Rossman, S. Ryu, V. Sekhri,
E. Sexton-Kennedy, I. Sfiligoi, S. Sharma, T.M. Shaw, D. Shpakov, E. Skup, R.P. Smith† , A. Soha,
W.J. Spalding, L. Spiegel, I. Suzuki, P. Tan, W. Tanenbaum, S. Tkaczyk1 , R. Trentadue1 , L. Uplegger, E.W. Vaandering, R. Vidal, J. Whitmore, E. Wicklund, W. Wu, J. Yarba, F. Yumiceva,
J.C. Yun
University of Florida, Gainesville, USA
D. Acosta, P. Avery, V. Barashko, D. Bourilkov, M. Chen, G.P. Di Giovanni, D. Dobur,
A. Drozdetskiy, R.D. Field, Y. Fu, I.K. Furic, J. Gartner, D. Holmes, B. Kim, S. Klimenko,
J. Konigsberg, A. Korytov, K. Kotov, A. Kropivnitskaya, T. Kypreos, A. Madorsky, K. Matchev,
G. Mitselmakher, Y. Pakhotin, J. Piedra Gomez, C. Prescott, V. Rapsevicius, R. Remington,
M. Schmitt, B. Scurlock, D. Wang, J. Yelton
Florida International University, Miami, USA
C. Ceron, V. Gaultney, L. Kramer, L.M. Lebolo, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez
Florida State University, Tallahassee, USA
T. Adams, A. Askew, H. Baer, M. Bertoldi, J. Chen, W.G.D. Dharmaratna, S.V. Gleyzer, J. Haas,
S. Hagopian, V. Hagopian, M. Jenkins, K.F. Johnson, E. Prettner, H. Prosper, S. Sekmen
Florida Institute of Technology, Melbourne, USA
M.M. Baarmand, S. Guragain, M. Hohlmann, H. Kalakhety, H. Mermerkaya, R. Ralich, I. Vodopiyanov
University of Illinois at Chicago (UIC), Chicago, USA
B. Abelev, M.R. Adams, I.M. Anghel, L. Apanasevich, V.E. Bazterra, R.R. Betts, J. Callner,
M.A. Castro, R. Cavanaugh, C. Dragoiu, E.J. Garcia-Solis, C.E. Gerber, D.J. Hofman, S. Khalatian, C. Mironov, E. Shabalina, A. Smoron, N. Varelas
28
A The CMS Collaboration
The University of Iowa, Iowa City, USA
U. Akgun, E.A. Albayrak, A.S. Ayan, B. Bilki, R. Briggs, K. Cankocak36 , K. Chung, W. Clarida,
P. Debbins, F. Duru, F.D. Ingram, C.K. Lae, E. McCliment, J.-P. Merlo, A. Mestvirishvili,
M.J. Miller, A. Moeller, J. Nachtman, C.R. Newsom, E. Norbeck, J. Olson, Y. Onel, F. Ozok,
J. Parsons, I. Schmidt, S. Sen, J. Wetzel, T. Yetkin, K. Yi
Johns Hopkins University, Baltimore, USA
B.A. Barnett, B. Blumenfeld, A. Bonato, C.Y. Chien, D. Fehling, G. Giurgiu, A.V. Gritsan,
Z.J. Guo, P. Maksimovic, S. Rappoccio, M. Swartz, N.V. Tran, Y. Zhang
The University of Kansas, Lawrence, USA
P. Baringer, A. Bean, O. Grachov, M. Murray, V. Radicci, S. Sanders, J.S. Wood, V. Zhukova
Kansas State University, Manhattan, USA
D. Bandurin, T. Bolton, K. Kaadze, A. Liu, Y. Maravin, D. Onoprienko, I. Svintradze, Z. Wan
Lawrence Livermore National Laboratory, Livermore, USA
J. Gronberg, J. Hollar, D. Lange, D. Wright
University of Maryland, College Park, USA
D. Baden, R. Bard, M. Boutemeur, S.C. Eno, D. Ferencek, N.J. Hadley, R.G. Kellogg, M. Kirn,
S. Kunori, K. Rossato, P. Rumerio, F. Santanastasio, A. Skuja, J. Temple, M.B. Tonjes, S.C. Tonwar, T. Toole, E. Twedt
Massachusetts Institute of Technology, Cambridge, USA
B. Alver, G. Bauer, J. Bendavid, W. Busza, E. Butz, I.A. Cali, M. Chan, D. D’Enterria, P. Everaerts,
G. Gomez Ceballos, K.A. Hahn, P. Harris, S. Jaditz, Y. Kim, M. Klute, Y.-J. Lee, W. Li, C. Loizides,
T. Ma, M. Miller, S. Nahn, C. Paus, C. Roland, G. Roland, M. Rudolph, G. Stephans, K. Sumorok,
K. Sung, S. Vaurynovich, E.A. Wenger, B. Wyslouch, S. Xie, Y. Yilmaz, A.S. Yoon
University of Minnesota, Minneapolis, USA
D. Bailleux, S.I. Cooper, P. Cushman, B. Dahmes, A. De Benedetti, A. Dolgopolov, P.R. Dudero,
R. Egeland, G. Franzoni, J. Haupt, A. Inyakin37 , K. Klapoetke, Y. Kubota, J. Mans, N. Mirman,
D. Petyt, V. Rekovic, R. Rusack, M. Schroeder, A. Singovsky, J. Zhang
University of Mississippi, University, USA
L.M. Cremaldi, R. Godang, R. Kroeger, L. Perera, R. Rahmat, D.A. Sanders, P. Sonnek, D. Summers
University of Nebraska-Lincoln, Lincoln, USA
K. Bloom, B. Bockelman, S. Bose, J. Butt, D.R. Claes, A. Dominguez, M. Eads, J. Keller, T. Kelly,
I. Kravchenko, J. Lazo-Flores, C. Lundstedt, H. Malbouisson, S. Malik, G.R. Snow
State University of New York at Buffalo, Buffalo, USA
U. Baur, I. Iashvili, A. Kharchilava, A. Kumar, K. Smith, M. Strang
Northeastern University, Boston, USA
G. Alverson, E. Barberis, O. Boeriu, G. Eulisse, G. Govi, T. McCauley, Y. Musienko38 , S. Muzaffar, I. Osborne, T. Paul, S. Reucroft, J. Swain, L. Taylor, L. Tuura
Northwestern University, Evanston, USA
A. Anastassov, B. Gobbi, A. Kubik, R.A. Ofierzynski, A. Pozdnyakov, M. Schmitt, S. Stoynev,
M. Velasco, S. Won
University of Notre Dame, Notre Dame, USA
L. Antonelli, D. Berry, M. Hildreth, C. Jessop, D.J. Karmgard, T. Kolberg, K. Lannon, S. Lynch,
29
N. Marinelli, D.M. Morse, R. Ruchti, J. Slaunwhite, J. Warchol, M. Wayne
The Ohio State University, Columbus, USA
B. Bylsma, L.S. Durkin, J. Gilmore39 , J. Gu, P. Killewald, T.Y. Ling, G. Williams
Princeton University, Princeton, USA
N. Adam, E. Berry, P. Elmer, A. Garmash, D. Gerbaudo, V. Halyo, A. Hunt, J. Jones, E. Laird,
D. Marlow, T. Medvedeva, M. Mooney, J. Olsen, P. Piroué, D. Stickland, C. Tully, J.S. Werner,
T. Wildish, Z. Xie, A. Zuranski
University of Puerto Rico, Mayaguez, USA
J.G. Acosta, M. Bonnett Del Alamo, X.T. Huang, A. Lopez, H. Mendez, S. Oliveros, J.E. Ramirez
Vargas, N. Santacruz, A. Zatzerklyany
Purdue University, West Lafayette, USA
E. Alagoz, E. Antillon, V.E. Barnes, G. Bolla, D. Bortoletto, A. Everett, A.F. Garfinkel, Z. Gecse,
L. Gutay, N. Ippolito, M. Jones, O. Koybasi, A.T. Laasanen, N. Leonardo, C. Liu, V. Maroussov,
P. Merkel, D.H. Miller, N. Neumeister, A. Sedov, I. Shipsey, H.D. Yoo, Y. Zheng
Purdue University Calumet, Hammond, USA
P. Jindal, N. Parashar
Rice University, Houston, USA
V. Cuplov, K.M. Ecklund, F.J.M. Geurts, J.H. Liu, D. Maronde, M. Matveev, B.P. Padley,
R. Redjimi, J. Roberts, L. Sabbatini, A. Tumanov
University of Rochester, Rochester, USA
B. Betchart, A. Bodek, H. Budd, Y.S. Chung, P. de Barbaro, R. Demina, H. Flacher, Y. Gotra,
A. Harel, S. Korjenevski, D.C. Miner, D. Orbaker, G. Petrillo, D. Vishnevskiy, M. Zielinski
The Rockefeller University, New York, USA
A. Bhatti, L. Demortier, K. Goulianos, K. Hatakeyama, G. Lungu, C. Mesropian, M. Yan
Rutgers, the State University of New Jersey, Piscataway, USA
O. Atramentov, E. Bartz, Y. Gershtein, E. Halkiadakis, D. Hits, A. Lath, K. Rose, S. Schnetzer,
S. Somalwar, R. Stone, S. Thomas, T.L. Watts
University of Tennessee, Knoxville, USA
G. Cerizza, M. Hollingsworth, S. Spanier, Z.C. Yang, A. York
Texas A&M University, College Station, USA
J. Asaadi, A. Aurisano, R. Eusebi, A. Golyash, A. Gurrola, T. Kamon, C.N. Nguyen, J. Pivarski,
A. Safonov, S. Sengupta, D. Toback, M. Weinberger
Texas Tech University, Lubbock, USA
N. Akchurin, L. Berntzon, K. Gumus, C. Jeong, H. Kim, S.W. Lee, S. Popescu, Y. Roh, A. Sill,
I. Volobouev, E. Washington, R. Wigmans, E. Yazgan
Vanderbilt University, Nashville, USA
D. Engh, C. Florez, W. Johns, S. Pathak, P. Sheldon
University of Virginia, Charlottesville, USA
D. Andelin, M.W. Arenton, M. Balazs, S. Boutle, M. Buehler, S. Conetti, B. Cox, R. Hirosky,
A. Ledovskoy, C. Neu, D. Phillips II, M. Ronquest, R. Yohay
Wayne State University, Detroit, USA
S. Gollapinni, K. Gunthoti, R. Harr, P.E. Karchin, M. Mattson, A. Sakharov
30
A The CMS Collaboration
University of Wisconsin, Madison, USA
M. Anderson, M. Bachtis, J.N. Bellinger, D. Carlsmith, I. Crotty1 , S. Dasu, S. Dutta, J. Efron,
F. Feyzi, K. Flood, L. Gray, K.S. Grogg, M. Grothe, R. Hall-Wilton1 , M. Jaworski, P. Klabbers,
J. Klukas, A. Lanaro, C. Lazaridis, J. Leonard, R. Loveless, M. Magrans de Abril, A. Mohapatra,
G. Ott, G. Polese, D. Reeder, A. Savin, W.H. Smith, A. Sourkov40 , J. Swanson, M. Weinberg,
D. Wenman, M. Wensveen, A. White
†: Deceased
1: Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland
2: Also at Universidade Federal do ABC, Santo Andre, Brazil
3: Also at Soltan Institute for Nuclear Studies, Warsaw, Poland
4: Also at Université de Haute-Alsace, Mulhouse, France
5: Also at Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des
Particules (IN2P3), Villeurbanne, France
6: Also at Moscow State University, Moscow, Russia
7: Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary
8: Also at University of California, San Diego, La Jolla, USA
9: Also at Tata Institute of Fundamental Research - HECR, Mumbai, India
10: Also at University of Visva-Bharati, Santiniketan, India
11: Also at Facolta’ Ingegneria Universita’ di Roma ”La Sapienza”, Roma, Italy
12: Also at Università della Basilicata, Potenza, Italy
13: Also at Laboratori Nazionali di Legnaro dell’ INFN, Legnaro, Italy
14: Also at Università di Trento, Trento, Italy
15: Also at ENEA - Casaccia Research Center, S. Maria di Galeria, Italy
16: Also at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
17: Also at California Institute of Technology, Pasadena, USA
18: Also at Faculty of Physics of University of Belgrade, Belgrade, Serbia
19: Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France
20: Also at Alstom Contracting, Geneve, Switzerland
21: Also at Scuola Normale e Sezione dell’ INFN, Pisa, Italy
22: Also at University of Athens, Athens, Greece
23: Also at The University of Kansas, Lawrence, USA
24: Also at Institute for Theoretical and Experimental Physics, Moscow, Russia
25: Also at Paul Scherrer Institut, Villigen, Switzerland
26: Also at Vinca Institute of Nuclear Sciences, Belgrade, Serbia
27: Also at University of Wisconsin, Madison, USA
28: Also at Mersin University, Mersin, Turkey
29: Also at Izmir Institute of Technology, Izmir, Turkey
30: Also at Kafkas University, Kars, Turkey
31: Also at Suleyman Demirel University, Isparta, Turkey
32: Also at Ege University, Izmir, Turkey
33: Also at Rutherford Appleton Laboratory, Didcot, United Kingdom
34: Also at INFN Sezione di Perugia; Universita di Perugia, Perugia, Italy
35: Also at KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary
36: Also at Istanbul Technical University, Istanbul, Turkey
37: Also at University of Minnesota, Minneapolis, USA
38: Also at Institute for Nuclear Research, Moscow, Russia
39: Also at Texas A&M University, College Station, USA
40: Also at State Research Center of Russian Federation, Institute for High Energy Physics,
Protvino, Russia
31