An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is presently under commissioning at Brookhaven National Laboratory (BNL) [1]. This facility enables testing of concepts relevant for high-energy coherent electron cooling,... more
An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is presently under commissioning at Brookhaven National Laboratory (BNL) [1]. This facility enables testing of concepts relevant for high-energy coherent electron cooling, electron-ion colliders, and high repetition rate FreeElectron Lasers. The ERL will be capable of providing electron beams with sufficient quality to produce high repetition rate THz and X-ray radiation. When completed the SRF photoinjector will provide 2 MeV energy and 300 mA average beam current. The injector for the RD this includes a 704MHz SRF gun with multi-alkali photocathode, cryo-system upgrade and a novel emittance preservation zigzag-like low energy merger system. We describe the design and major components of the R&D ERL injector then report the first experimental results and experiences learned in the first stage of beam commissioning of the BNL R&D ERL.
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A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under commissioning at BNL. Without a cathode insert, the SRF gun achieved its design goal: an accelerating voltage of 2 MV in CW mode. During... more
A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under commissioning at BNL. Without a cathode insert, the SRF gun achieved its design goal: an accelerating voltage of 2 MV in CW mode. During commissioning with a copper cathode insert, it reached 1.9 MV with 18% duty factor, which is limited by multipacting in a choke-joint cathode stalk. A new cathode stalk has been designed to eliminate multipacting in the choke-joint. At the same time, a first beam test was carried out in May this year, and dark current from the photocathode was measured in the faraday cup. The SRF cavity was tested after the beam commissioning and shows no-degradation of the performance. This paper presents recent commissioning setup, results and plans for the future beam tests.
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The 704 MHz SRF gun successfully generated the first photoemission beam in November of 2014. The configurations of the test and the sub-systems are described.The latest results of SRF commissioning, including the cavity performance,... more
The 704 MHz SRF gun successfully generated the first photoemission beam in November of 2014. The configurations of the test and the sub-systems are described.The latest results of SRF commissioning, including the cavity performance, cathode QE measurements, beam current/energy measurements, are presented in the paper.
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A 56 MHz Superconducting RF Storage Cavity is being constructed for the RHIC collider. This cavity is a quarter wave resonator that will be operated in a liquid helium bath at 4.4 K. The cavity requires an extremely quiet environment to... more
A 56 MHz Superconducting RF Storage Cavity is being constructed for the RHIC collider. This cavity is a quarter wave resonator that will be operated in a liquid helium bath at 4.4 K. The cavity requires an extremely quiet environment to maintain its operating frequency. The cavity, besides being engineered for a mechanically quiet system, also requires a quiet cryogenic system. The helium is taken from RHIC’s main helium supply header at 3.5 atm, 5.3K at a phase separator tank. The boil-off is sent back to the RHIC refrigeration system to recover the cooling. To acoustically separate the RHIC helium supply and return lines, a condenser/boiler heat exchanger condenses the helium vapor generated in the RF cavity bath. A system description and operating parameters are given about the cryogen delivery system. INTRODUCTION A 56 MHz superconducting RF storage cavity is planned to be installed in the RHIC IP4 area to provide a large longitudinal bucket for stored bunches of ion beams and h...
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The muon (g{minus}2) experiment at Brookhaven has just completed a 3-month run for checkout and initial data-taking. In the first two months beam was taken in a parasitic mode where one out of ten AGS pulses was delivered for... more
The muon (g{minus}2) experiment at Brookhaven has just completed a 3-month run for checkout and initial data-taking. In the first two months beam was taken in a parasitic mode where one out of ten AGS pulses was delivered for commissioning of the beam line, quadrupoles, detectors, and data acquisition system. This was followed by four weeks of dedicated data collection. The main components of the experiment, which include the pion/muon beam line, the superconducting inflector, the superferric storage ring with its pulsed electric quadrupoles and magnetic field measurement system, and the detector system based on lead-scintillating fiber electron calorimeters, have been satisfactorily commissioned. The muon (g{minus}2) precession frequency is clearly seen as a large signal. It is estimaed that over 25{times}10{sup 6} decay positrons with energies greater than 1.5 GeV have been detected. {copyright} {ital 1997 American Institute of Physics.}
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The muon g-2 experiment at Brookhaven National Laboratory has constructed a 7.112m radius superconducting magnet. The design and construction of the storage ring magnet are described. 1
The R&D ERL project at BNL aims to demonstrate a high charge, high current Energy Recovery Linac (ERL). One of the key ERL systems is the 704 MHz half-cell Superconducting RF (SRF) photoemission gun. The SRF gun is designed to deliver up... more
The R&D ERL project at BNL aims to demonstrate a high charge, high current Energy Recovery Linac (ERL). One of the key ERL systems is the 704 MHz half-cell Superconducting RF (SRF) photoemission gun. The SRF gun is designed to deliver up to 0.5 ampere beam at 2 MeV with 1 MW of CW RF power. The gun commissioning in the ERL block house started in November of 2012. After high power RF conditioning, the cavity is now able to operate at 2 MV in CW mode. This paper briefly addresses the SRF gun system design, then describes the cold emission tests and discusses the results.
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The BNL 704 MHz SRF gun for R&D Energy Recovery Linac (ERL) successfully generated the first photoemission beam in November of 2014, with a copper substrate cathode stalk. A new multipacting-free, Tasubstrate cathode stalk was designed,... more
The BNL 704 MHz SRF gun for R&D Energy Recovery Linac (ERL) successfully generated the first photoemission beam in November of 2014, with a copper substrate cathode stalk. A new multipacting-free, Tasubstrate cathode stalk was designed, fabricated and demonstrated as truly multipacting free. With this new cathode stalk, the beam commissioning has been continued to bring the beam to dump, which is called Gun-to-dump commissioning. This paper discusses the first beam commissioning, design and commissioning of multipacting-free cathode stalk. ERL commissioning status will be addressed as well.
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The 703 MHz superconducting gun for the BNL Energy Recovery Linac (ERL) prototype has two fundamental power couplers (FPCs), and each of them will deliver up to 500 kW of CW RF power. In order to prepare the couplers for high power RF... more
The 703 MHz superconducting gun for the BNL Energy Recovery Linac (ERL) prototype has two fundamental power couplers (FPCs), and each of them will deliver up to 500 kW of CW RF power. In order to prepare the couplers for high power RF service and process multipacting, the FPCs should be conditioned prior to installation into the gun cryomodule. A conditioning cart based test stand, which includes a vacuum pumping system, controllable bake-out system, diagnostics, interlocks and data log system has been designed, constructed and commissioned by collaboration of BNL and AES. This paper presents FPC conditioning cart systems and the conditioning process for the BNL GUN FPCs.
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A vertical test facility has been constructed to test SRF cavities and can be utilized for other applications. The liquid helium volume for the large vertical dewar is approximate 2.1m tall by 1m diameter with a clearance inner diameter... more
A vertical test facility has been constructed to test SRF cavities and can be utilized for other applications. The liquid helium volume for the large vertical dewar is approximate 2.1m tall by 1m diameter with a clearance inner diameter of 0.95m after the inner cold magnetic shield installed. For radiation enclosure, the test dewar is located inside a concrete block structure. The structure is above ground, accessible from the top, and equipped with a retractable concrete roof. A second radiation concrete facility, with ground level access via a labyrinth, is also available for testing smaller cavities in 2 smaller dewars. The cryogenic transfer lines installation between the large vertical test dewar and the cryo plant's sub components is currently near completion. Controls and instrumentations wiring are also nearing completion. The Vertical Test Facility will allow onsite testing of SRF cavities with a maximum overall envelope of 0.9 m diameter and 2.1 m height in the large d...
The BNL 704MHz SRF gun has a grooved choke joint to support the photo-cathode. Due to the distortion of grooves at the choke joint during the BCP for the choke joint, several multipacting barriers showed up when it was tested with Nb... more
The BNL 704MHz SRF gun has a grooved choke joint to support the photo-cathode. Due to the distortion of grooves at the choke joint during the BCP for the choke joint, several multipacting barriers showed up when it was tested with Nb cathode stalk at JLab. We built a setup to use the spare large grain SRF cavity to test and condition the multipacting at BNL with various power sources up to 50kW. The test is carried out in three stages: testing the cavity performance without cathode, testing the cavity with the Nb cathode stalk that was used at Jlab, and testing the cavity with a copper cathode stalk that is based on the design for the SRF gun. This paper summarizes the results of multipacting simulation, and presents the large grain cavity test setup and the test results.
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The Coherent electron Cooling (CeC) Proof of Principle (PoP) experiment is proposed to be installed in the Relativistic Heavy Ion Collider (RHIC) to demonstrate proton and ion beam cooling with this new technique that may increase the... more
The Coherent electron Cooling (CeC) Proof of Principle (PoP) experiment is proposed to be installed in the Relativistic Heavy Ion Collider (RHIC) to demonstrate proton and ion beam cooling with this new technique that may increase the beam luminosity in certain cases, by as much as tenfold. Within the scope of this project, a 112 MHz, 2MeV Superconducting Radio Frequency (SRF) electron gun and a 704 MHz 20MeV 5-cell SRF cavity will be installed at IP2 in the RHIC ring. The superconducting RF electron gun will be cooled in a liquid helium bath at 4.4 K. The 704 MHz 5-cell SRF cavity will be cooled in a super-fluid helium bath at 2.0 K. This paper discusses the cryogenic systems designed for both cavities. For the 112 MHz cavity cryogenic system, a condenser/boiler heat exchanger is used to isolate the cavity helium bath from pressure pulses and microphonics noise sources. For the 704 MHz 5-cell SRF cavity, a heat exchanger is also used to isolate the SRF cavity helium bath from noise sources in the sub-atmospheric pumping system operating at room temperature. Detailed designs, thermal analyses and discussions for both systems will be presented in this paper.
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In order to cool the superconducting magnets in RHIC, its helium refrigerator distributes 4.5 K helium throughout the tunnel along with helium distribution for the magnet line recoolers, the heat shield, and the associated return lines.... more
In order to cool the superconducting magnets in RHIC, its helium refrigerator distributes 4.5 K helium throughout the tunnel along with helium distribution for the magnet line recoolers, the heat shield, and the associated return lines. The worse case for failure would be a release from the magnet distribution line which operates at 3.5 to 4.5 atmospheres and contains the energized magnet but with a potential energy of 70 MJoules should the insulation system fail or an electrical connection opens. Studies were done to determine release rate of the helium and the resultant reduction in O{sub 2} concentration in the RHIC tunnel and service buildings. Equipment and components were also reviewed for design and reliability and modifications were made to reduce the likelihood of failure and to reduce the volume of helium that could be released.
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A vertical test facility has been constructed to test SRF cavities and can be utilized for other applications. The liquid helium volume for the large vertical dewar is approximate 2.1m tall by 1m diameter with a clearance inner diameter... more
A vertical test facility has been constructed to test SRF cavities and can be utilized for other applications. The liquid helium volume for the large vertical dewar is approximate 2.1m tall by 1m diameter with a clearance inner diameter of 0.95m after the inner cold magnetic shield installed. For radiation enclosure, the test dewar is located inside a concrete block structure. The structure is above ground, accessible from the top, and equipped with a retractable concrete roof. A second radiation concrete facility, with ground level access via a labyrinth, is also available for testing smaller cavities in 2 smaller dewars. The cryogenic transfer lines installation between the large vertical test dewar and the cryo plant's sub components is currently near completion. Controls and instrumentations wiring are also nearing completion. The Vertical Test Facility will allow onsite testing of SRF cavities with a maximum overall envelope of 0.9 m diameter and 2.1 m height in the large d...
We report a variation of the pseudogene for the serotonin-7 receptor in human DNA. Human genomic DNA was amplified, using the polymerase chain reaction method and degenerate oligonucleotide primers for serotonin receptor-like genes. A... more
We report a variation of the pseudogene for the serotonin-7 receptor in human DNA. Human genomic DNA was amplified, using the polymerase chain reaction method and degenerate oligonucleotide primers for serotonin receptor-like genes. A novel gene DNA sequence of 1325 bp was found. Based on nucleotides, this gene is 88% identical to the serotonin-7 receptor coding sequence. Compared with the previously known serotonin-7 receptor pseudogene, this pseudogene has 1 nucleotide deletion and 4 nucleotide mutations. The gene is located on human chromosome 12 at 12p12.3-p13.2.
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HORIZONTAL BEAM VIBRATION AROUND 10HZ IN THE RELATIVISTIC HEAVY ION COLLIDER (RHIC) HAVE BEEN IDENTIFIED AND THE POSSIBLE SOURCES TO CAUSE THIS VIBRATION HAVE BEEN INVESTIGATED. TO DETERMINE THE HETIUM PRESSURE OSCILLATIONS AS A POSSIBLE... more
HORIZONTAL BEAM VIBRATION AROUND 10HZ IN THE RELATIVISTIC HEAVY ION COLLIDER (RHIC) HAVE BEEN IDENTIFIED AND THE POSSIBLE SOURCES TO CAUSE THIS VIBRATION HAVE BEEN INVESTIGATED. TO DETERMINE THE HETIUM PRESSURE OSCILLATIONS AS A POSSIBLE PRIMARY VIBRATION SOURCE, HELIUM PRESSURE MEASUREMENTS WERE CARRIED OUT IN THE FIVE CRYOGENIC TRANSFER LINES AT 2 VALVE BOXES AND 6 LEAD PORTS AT 2
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Mechanical vibrations of accelerator components have been studied in the context of various colliders, both existing ones like HERA [1], [2] and [3] or the TEVATRON [4] and [5], and future projects like the Linear Collider [6], [7] and... more
Mechanical vibrations of accelerator components have been studied in the context of various colliders, both existing ones like HERA [1], [2] and [3] or the TEVATRON [4] and [5], and future projects like the Linear Collider [6], [7] and [8]. In each case, there is a serious concern ...
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One of the main reasons for this uncertain role of serotonin2A receptors in antipsychotic action stems from the uncertain values for the dissociation constants of the various antipsychotic drugs at the serotonin receptors. These values... more
One of the main reasons for this uncertain role of serotonin2A receptors in antipsychotic action stems from the uncertain values for the dissociation constants of the various antipsychotic drugs at the serotonin receptors. These values vary considerably among ...
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Instrumenting the new AGS (Alternating Gradient Synchrotron) Booster required the construction of a great deal of support electronics for many beam monitoring devices. Modules providing generic functions such as amplification,... more
Instrumenting the new AGS (Alternating Gradient Synchrotron) Booster required the construction of a great deal of support electronics for many beam monitoring devices. Modules providing generic functions such as amplification, integration, sample and hold, etc., were designed and packaged so as to provide maximum flexibility in the implementation of typical instrumentation tasks. The authors describe these modules and include some
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In order to cool the superconducting magnets in RHIC, its helium refrigerator distributes 4.5 K helium throughout the tunnel along with helium distribution for the magnet line recoolers, the heat shield, and the associated return lines.... more
In order to cool the superconducting magnets in RHIC, its helium refrigerator distributes 4.5 K helium throughout the tunnel along with helium distribution for the magnet line recoolers, the heat shield, and the associated return lines. The worse case for failure would be a release from the magnet distribution line which operates at 3.5 to 4.5 atmospheres and contains the
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A 56 MHz Superconducting RF Storage Cavity is being constructed for the RHIC collider. This cavity is a quarter wave resonator that will be operated in a liquid helium bath at 4.4 K. The cavity requires an extremely quiet environment to... more
A 56 MHz Superconducting RF Storage Cavity is being constructed for the RHIC collider. This cavity is a quarter wave resonator that will be operated in a liquid helium bath at 4.4 K. The cavity requires an extremely quiet environment to maintain its operating frequency. The cavity, besides being engineered for a mechanically quiet system, also requires a quiet cryogenic
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The muon (g-2) experiment at Brookhaven has just completed a 3-month run for checkout and initial data-taking. In the first two months beam was taken in a parasitic mode where one out of ten AGS pulses was delivered for commissioning of... more
The muon (g-2) experiment at Brookhaven has just completed a 3-month run for checkout and initial data-taking. In the first two months beam was taken in a parasitic mode where one out of ten AGS pulses was delivered for commissioning of the beam line, quadrupoles, detectors, and data acquisition system. This was followed by four weeks of dedicated data collection. The main components of the experiment, which include the pion/muon beam line, the superconducting inflector, the superferric storage ring with its pulsed electric quadrupoles and magnetic field measurement system, and the detector system based on lead-scintillating fiber electron calorimeters, have been satisfactorily commissioned. The muon (g-2) precession frequency is clearly seen as a large signal. It is estimaed that over 25×106 decay positrons with energies greater than 1.5 GeV have been detected.
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... In order to prevent the 1.45 T field from entering the beam tube, the Eddy current generated on the outer surface of the tube must be significant, and these large currents would also affect the main field uniformity in the muon... more
... In order to prevent the 1.45 T field from entering the beam tube, the Eddy current generated on the outer surface of the tube must be significant, and these large currents would also affect the main field uniformity in the muon storage region. Fig. ...
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The g-2 muon storage ring magnet system consists of four large superconducting solenoids that are up to 15.1 m in diameter. The g-2 superconducting solenoids and a superconducting inflector dipole will be cooled using forced two-phase... more
The g-2 muon storage ring magnet system consists of four large superconducting solenoids that are up to 15.1 m in diameter. The g-2 superconducting solenoids and a superconducting inflector dipole will be cooled using forced two-phase helium in tubes. The forced two-phase helium cooling will be provided from the J-T circuit of a refrigerator that is capable of delivering 625 W at 4.5 K. The two-phase helium flows from the refrigerator J-T circuit through a heat exchanger in a storage dewar that acts as a phase separator for helium returning from the magnets. The use of a heat exchanger in the storage dewar reduces the pressure drop in the magnet flow circuit, eliminates most two phase flow oscillations, and it permits the magnets to operate at variable thermal loads using the liquid in the storage dewar as a buffer. The g-2 magnet cooling system will consist of three parallel two-phase helium flow circuits that provide cooling to the following components: (1) the four large supercon...