Particle detectors

The EUDET-project was launched to create an infrastructure for developing and testing new and
advanced detector technologies to be used at a future linear collider. The aim was to make possible
experimentation and analysis of data for institutes, which otherwise could not be realized due to lack
of resources. The infrastructure comprised an analysis and software network, and instrumentation
infrastructures for tracking detectors as well as for calorimetry.

The method of cosmic ray neutron sensing - measuring soil moisture non-invasively at the hectometer scale has turned out to be feasible by detecting the environmental albedo neutron density. The key feature of the method is that neutrons generated by cosmic rays show an exceptionally different behavior interacting with hydrogen. It slows down fast neutrons whereas any other heavier element, independent of the chemical composition, rather reflects them. In the recent years the understanding of neutron transport by Monte Carlo simulations led to major advancements in precision, which have been successfully targeted meanwhile by a manifold of experiments.
We are now developing boron-lined neutron detectors using spin-off technologies from the upcoming European Spallation Source and instrument design experience from past experiments. These detectors shall also offer an alternative platform to current Helium-3 based systems. In order to reduce costs we recently have developed readout electronics and data acquistion systems based on Arduino microcontrollers.

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of ...

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of ...

With the Arduino open source electronics platform microcontrollers have become a comparably easy-to-use tool for rapid prototyping and implementing creative solutions. Their stability especially qualifies them to be used for slow control units. Yet, running at 16 MHz, the capabilities can be extended to data taking and signal analysis at decent rates. Such devices in combination with dedicated frontend electronics can offer low cost alternatives for student projects and independently operating small scale instrumentation. We present two projects, which cover as well the readout of helium-3 and boron-10 proportional counters as of scintillators or wavelength shifting fibers with Silicon Photomultipliers.
The nCatcher combines commercially available analog electronics and the Arduino nano enabling pulse shape analysis for proportional counters. The frontend integrates and shapes pulses to microseconds in order to use the Arduino's signal analysis capabilities - time over threshold measurement and a 10-bit analog to digital converter. Combining these two parameters allows for effective discrimination between different radiation types by estimating the total deposited energy (E) of incoming radiation as well as the mean energy loss per distance (dE/dx). This makes the device suitable for low to medium rate environments, where a good signal noise is a crucial.
With the SiPMTrigger we have realized a small scale design for triggering or vetoing. It consists of a custom mixed signal frontend board featuring signal amplification, discrimination and a coincidence unit. An Arduino MEGA digitally adjusts the thresholds of both channels and measures the trigger rate up to 200 kHz.

A 1-meter-long trapezoidal Triple-GEM detector with wide readout strips was tested in hadron beams at the Fermilab Test Beam Facility in October 2013. The readout strips have a special zigzag geometry and run along the radial direction with an azimuthal pitch of 1.37 mrad to measure the azimuthal φ-coordinate of incident particles. The zigzag geometry of the readout reduces the required number of electronic channels by a factor of three compared to conventional straight readout strips while preserving good angular resolution. The average crosstalk between zigzag strips is measured to be an acceptable 5.5%. The detection efficiency of the detector is (98.4 ± 0.2)%. When the non-linearity of the zigzag-strip response is corrected with track information, the angular resolution is measured to be (193 ± 3) µrad, which corresponds to 14% of the angular strip pitch. Multiple Coulomb scattering effects are fully taken into account in the data analysis with the help of a stand-alone Geant4 simulation that estimates interpolated track errors.

The Indium antimonide (InSb) is one of the promising optoelectronic materials having potential applications in the development of data storage, frequency, parametric oscillations, detectors and related gadgets. Purity of material plays a vital role in the development of quality devices for space and defence related high-end applications. Directional Solidification System (DSS) plays a major role in reducing the vibrations during the synthesis and crystallization process to yield high and pure InSb compound. This paper discusses homogenization, synthesis, purification and characterization of Indium antimonide. Directional Solidification System (DSS) is employed for the preparation of pure InSb crystalline material. This system is fabricated with a view to establish required and suitable temperature isotherms at top and bottom of the furnace and also to tackle the irregularities of sample during the process of cooling the aspects. The crystallization of homogenized pure sample is kept under vacuum in the furnace. The impurities of the InSb are segregated at the bottom end of the sample. The purity analysis of the InSb sample is studied and presented by employing XRD, TEM, SEM, EDS, ICP-OES, Raman and FTIR techniques.

The world of detectors used in thermal neutron scattering instrumentation has changed. By alerts on the future Helium-3 supply, critical to perspectives of the large-scale research infrastructures, the run on substitutional technologies started. Most of the solutions could be adapted from developments of particle physics and are comprised of one or more layers of Boron-10. The Time Projection Method achieves a very high resolution by projecting ionization tracks onto a readout with dense spatial and time information. The university of Bonn is developing a novel system employing the TimePix technology - CMOS based chips with 55 micrometer sized pixels operated at clock speeds up to 80 MHz. In a first prototype with 8 TimePix chips, which are arranged in parallel to a boron layer, the track topology with this unrivaled high resolution has been studied. By reconstructing the origin of the conversion ions a time resolution of <50 ns and a spatial resolution of 100 micrometer has been achieved.

Energetic and high fluence helium ions emitted in a plasma focus device have been used successfully to
study the radiation induced damage on tungsten. The reference and irradiated samples were characterized
by optical microscopy, field emission scanning electron microscopy, X-ray diffraction and by hardness
testers. The micrographs of the irradiated samples at lower magnification show uniform mesh of
cracks of micrometer width. However at higher magnification, various types of crystalline defects such
as voids, pinholes, bubbles, blisters and microcracks are distinctly noticed. The prominent peaks in
X-ray diffraction spectrum of irradiated samples are seen shifted toward higher Bragg angles, thus indicating
accumulation of compressive stress due to the heat load delivered by helium ions. A marginal
reduction in hardness of the irradiated sample is also noticed.

The world of detectors used in thermal neutron scattering instrumentation has changed. By alerts on the future Helium-3 supply, critical to perspectives of the large-scale research infrastructures, the run on substitutional technologies started. Most of the solutions could be adapted from developments of particle physics and are comprised of one or more layers of Boron-10. The Time Projection Method achieves a very high resolution by projecting ionization tracks onto a readout with dense spatial and time information. The university of Bonn is developing a novel system employing the TimePix technology - CMOS based chips with 55 micrometer sized pixels operated at clock speeds up to 80 MHz. In a first prototype with 8 TimePix chips, which are arranged in parallel to a boron layer, the track topology with this unrivaled high resolution has been studied. By reconstructing the origin of the conversion ions a time resolution of <50 ns and a spatial resolution of 100 micrometer has been achieved.

The globally increased demand of Helium-3 along with the limited availability for this gas asks for the development of alternative technologies as the nowadays standard technology is still based on the Helium counter tube.
We report on the CASCADE Project - a novel detection system, which has been developed for the purposes of neutron spin echo spectroscopy. It features 2D spatially resolved detection of thermal neutrons at high rates. The CASCADE detector is comprised of a stack of solid 10B coated Gas Electron Multiplier (GEM) foils, which serve both as a neutron converter and as an amplifier for the primary ionization deposited in the standard Argon-CO2 counting gas environment.
For the application in MIEZE spin echo techniques it has furthermore been managed to extract the signal of the charge traversing the stack to identify the very thin conversion layer of about 1μm. This allows to precisely determine the time-of-flight [2].
The detector concept and measurement results will be presented.

[1] M. Klein, C.J. Schmidt, Nucl. Instr. and Meth. A 628 (2011) 9-18
[2] W. Häussler et al., J. Phys.: Conf. Ser. 251 012067 (2010)

Talk Presented at the International Workshop on Position Sensitive Neutron Detectors, 2014

The method of cosmic ray neutron sensing - soil moisture measurement at the hectometer scale non-invasively has turned out to be feasible by detecting environmental albedo neutron density. The key feature of the method is the exceptionally different behavior of hydrogen in its reflction power of neutrons generated by cosmic rays. It slows down fast neutrons whereas any other heavier element independent of the chemical composition rather reflects them. In the recent years the understanding of neutron transport by Monte-Carlo simulations led to major advancements in precision, which have been successfully targeted meanwhile by a manifold of experiments. Whereas the homogeneous conditions are well understood, inhomogeneous topologies are now in the focus of research. In our case these are applications for partial snow cover and mobile surveys, where the influence of the road material, which biased results towards lower soil moisture values, could be calculated, measured and analytically understood. Here we present the actual status of the method especially with respect to inhomogeneous terrain.

The world of detectors used in thermal neutron scattering instrumentation has changed. By alerts on the future Helium-3 supply, critical to perspectives of the large-scale research infrastructures the run on substitutional technologies started. Most of the solutions could be adapted from developments of particle physics and are comprised of one or more layers of Boron-10. The Time Projection Method achieves highest spatial and time information by high granular track reconstruction, here by the conversion products in a solid Boron-10 layer. Based on the experience of the CASCADE Detector installed at the Spin-Echo instruments RESEDA and MIRA at FRM II in Germany, the University of Bonn now develops two novel systems using the Time Projection Method. The BASTARD detector based on Gas Electron Multiplier foils aims for sub-millimeter resolution at highest count rates and the BODELAIRE detector based on TimePix chips aims for sub-100 micrometer resolution at medium count rates. Both systems increase the efficiency of a single layer of Boron-10 by stacking several consecutive units in beam direction. We present the actual status of the CASCADE project and the actual developments of the novel detector prototypes.

A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN.

We introduce an original model of quantum phenomena, a model that provides a picture of a "deep structure", an "underlying pattern" of quantum dynamics. We propose that the source of a particle and all of that particle's possible detectors "talk" before the particle is finally observed by just one detector. These talks do not take place in physical time. They occur in what we call "hidden time". Talks are spatially organized in such a way that the model reproduces standard quantum probability amplitudes. This is most obviously seen if one uses R. Feynman's formulation of quantum theory. We prefer the "physical level" of mathematical strictness in describing our model.

In the last few years CMOS commercial technologies of the quarter micron node have been extensively used in the design of the readout electronics for highly granular detection systems in the particle physics environment. IC designers are now moving to 130 nm CMOS technologies, or even to the next technology generation, to implement readout integrated circuits for future HEP applications.

We examine a maximum-a-posteriori method for estimating the primary interaction position of gamma rays with multiple interaction sites (hits) in a monolithic detector. In assessing the performance of a multiple-hit estimator over that of a conventional one-hit estimator, we consider a few different detector and readout configurations of a 50-mm-wide square cerium-doped lutetium oxyorthosilicate block. For this study, we use simulated data from SCOUT, a Monte-Carlo tool for photon tracking and modeling scintillation- camera output. With this tool, we determine estimate bias and variance for a multiple-hit estimator and compare these with similar metrics for a one-hit maximum-likelihood estimator, which assumes full energy deposition in one hit. We also examine the effect of event filtering on these metrics; for this purpose, we use a likelihood threshold to reject signals that are not likely to have been produced under the assumed likelihood model. Depending on detector design, we observe a 1%-12% improvement of intrinsic resolution for a 1-or-2-hit estimator as compared with a 1-hit estimator. We also observe improved differentiation of photopeak events using a 1-or-2-hit estimator as compared with the 1-hit estimator; more than 6% of photopeak events that were rejected by likelihood filtering for the 1-hit estimator were accurately identified as photopeak events and positioned without loss of resolution by a 1-or-2-hit estimator; for PET, this equates to at least a 12% improvement in coincidence-detection efficiency with likelihood filtering applied.

Bisher werden zum effizienten Nachweis von thermischen Neutronen Detektoren auf Basis von Helium-3 eingesetzt, welches sowohl als Neutronenkonverter wie auch als Zählgas dient. Die weltweit gestiegene Nachfrage verlangt, einhergehend mit der limitierten Verfügbarkeit, nach der Entwicklung alternativer Technologien, insbesondere auch in Hinblick auf die ESS.
Der CASCADE-Detektor wurde zum Einsatz in der ortsaufgelösten Neutronen-Spinechospektroskopie entwickelt. Das neuartige Detektionssystem nutzt Bor-10 beschichtete Gas Electron Multiplier (GEM) Folien, mittels deren Neutronenkonversion und nachfolgend Gasverstärkung der entstehenden Primärionisation erfolgt. Die Nachweiseffizienz wird damit durch die Zahl an Folien im Stapel erhöht.
Für die Anwendung in Spinechomessungen (MIEZE) mit thermischen Neutronen wird durch Auslesen des Ladungssignals an einzelnen GEM-Lagen die Konversionsschicht identifiziert und somit präzise die Neutronflugzeit bestimmt. Die kompakte Bauweise erlaubt in Kombination mit der hohen Zeitauflösung das Abbilden der wenige Zentimeter ausgedehnten Spinechogruppe.

Talk Presented at the Deutsche Tagung für Forschung mit Synchrotronstrahlung, Neutronen und Ionenstrahlen an Großgeräten, 2014