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R&D ERL: Magnet

Description: The BNL prototype ERL is the major experimental research and development effort towards RHIC II, the electron cooling project for RHIC. The objective is to reduce the risk and costs of the RHIC II project, as well as developing and demonstrating the electron beam parameters required for electron cooling. The prototype will also serve as a test bed for studying issues relevant to very high current ERLs. All quadrupole and dipole magnets are of the warm bore variety. All magnets are to be accurately CNC machined and will be installed on similarly machined bases. A portion of the ring will be mounted on a movable gantry with a total stroke of plus/minus 5cm.
Date: January 1, 2010
Creator: Mahler, G.
Partner: UNT Libraries Government Documents Department

A field-deployable gamma-ray spectrometer utilizing xenon at high pressure

Description: Prototype gamma-ray spectrometers utilizing xenon gas at high pressure, suitable for applications in the nuclear safeguards, arms control, and nonproliferation communities, have been developed at Brookhaven National Laboratory (BNL). These spectrometers function as ambient-temperature ionization chambers detecting gamma rays with good efficiency in the energy range 50 keV - 2 MeV, with an energy resolution intermediate between semiconductor (Ge) and scintillation (NaI) spectrometers. They are capable of prolonged, low-power operation without a requirement for cryogenic fluids or other cooling mechanisms, and with the addition of small quantities of {sup 3}He gas, can function simultaneously as efficient thermal neutron detectors.
Date: October 1, 1996
Creator: Smith, G.C.; Mahler, G.J.; Yu, B.; Salwen, C.; Kane, W.R. & Lemley, J.R.
Partner: UNT Libraries Government Documents Department

A field-deployable gamma-ray spectrometer utilizing high pressure xenon

Description: Most nuclear materials in the nuclear energy, safeguards, arms control, and nonproliferation regimes emit gamma rays with a unique signature. Currently, two categories of spectrometers are available to evaluate these materials: (1) Semiconductors, with excellent energy resolution, which operate at cryogenic temperatures. (2) Scintillation detectors, which function at ambient temperature, but with poor energy resolution. A detector which functions for extended periods in a range of environments, with an energy resolution superior to that of a scintillation spectrometer, would have evident utility. Recently, in the research community, such a device has evolved, an ionization chamber utilizing xenon gas at very high pressure (60 atm). Its energy resolution, typically, is 20 keV for the 661 keV gamma ray of {sup 137}Cs. With high xenon density and its high atomic number (Z=54), and superior energy resolution, its sensitivity is comparable to that of a scintillator.
Date: May 1, 1997
Creator: Smith, G.C.; Mahler, G.J.; Yu, Bo; Kane, W.R. & Lemley, J.R.
Partner: UNT Libraries Government Documents Department

Small gap magnet prototype measurements for eRHIC

Description: In this paper we present the design and prototype measurement of small gap (5mm to 10 mm aperture) dipole and quadrupole for the future high energy ERL (Energy Recovery Linac). The small gap magnets have the potential of largely reducing the cost of the future electron-ion collider project, eRHIC, which requires a 10GeV to 30 GeV ERL with up to 6 energy recovery passes (3.8 km each pass). We also studied the sensitivity of the energy recovery pass and the alignment error in this small magnets structure and countermeasure methods.
Date: May 23, 2010
Creator: Hao, Y.; He, P.; Jain, A.; Mahler, G.; Meng, W.; Tuozzolo, J. et al.
Partner: UNT Libraries Government Documents Department

SNS RING INJECTION STRIPPED ELECTRON COLLECTION: DESIGN ANALYSIS AND TECHNICAL ISSUES.

Description: This paper describes the simulation studies on the motions of stripped electrons generated in the injection section of the Spallation Neutron Source (SNS) accumulator ring and the effective collection mechanism. Such studies are important for high intensity machines, in order to reduce beam loss and protect other components in the vicinity. The magnetic field is applied to guide electrons to a collector, which is located at the bottom of the beam vacuum chamber. Part of the study results with and without considering the interactions between electrons and materials are presented and discussed. The final engineering design of the electron collector (catcher). The electron multi-pacting induced by beam loss and residual gas ionization along the ring has been studied in detail [l]. In the SNS accumulator ring straight section, electrons are stripped from the injected H{sup -} beam through a carbon foil. These protons must make 1100 turns to be compressed from 1 ms Linac pulse into a 700 ns bunch with 2E14 protons. The stripped electrons will have the same initial velocity but twice the intensity (current) of the H{sup -} beam. In this paper, we report the studies on electrons, and the optimum design of the collector.
Date: May 16, 2005
Creator: LEE, Y.; MAHLER, G.; MENG, W.; RAPARIA, D.; WANG, L. & WEI, J.
Partner: UNT Libraries Government Documents Department

Small gap magnets and vacuum chambers for eRHIC

Description: eRHIC[1][2][3], a future high luminosity electron-ion collider at Brookhaven National Laboratory (BNL), will add polarized electrons to the list of colliding species in RHIC. A 10-30 GeV electron energy recovery linac (ERL) will require up to six passes around the RHIC 3.8 km circumference. We are developing and testing small (5 mm) gap dipole and quadrupole magnets and vacuum chambers for cost-effective eRHIC passes [4]. We are also studying the sensitivity of eRHIC pass optics to magnet and alignment errors in such a small magnet structure. We present the magnetic and mechanical designs of the small gap eRHIC components and prototyping test progress.
Date: May 4, 2009
Creator: Meng,W.; Bengtsson, J.; Hao, Y.; Mahler, G.; Tuozzolo, J. & Litvinenko, V. N.
Partner: UNT Libraries Government Documents Department

Gamma-ray spectrometer utilizing xenon at high pressure

Description: A prototype gamma-ray spectrometer utilizing xenon gas near the critical point (166{degrees}C, 58 atm) is under development. The spectrometer will function as a room-temperature ionization chamber detecting gamma rays in the energy range 100 keV2 MeV, with an energy resolution intermediate between semiconductor (Ge) and scintillation (NaI) spectrometers. The energy resolution is superior to that of a NaI scintillation spectrometer by a substantial margin (approximately a factor 5), and accordingly, much more information can be extracted from a given gamma-ray spectrum. Unlike germanium detectors, the spectrometer possesses the capability for sustained operation under ambient temperature conditions without a requirement for liquid nitrogen.
Date: August 1, 1994
Creator: Smith, G. C.; Mahler, G. J.; Yu, B.; Kane, W. R. & Markey, J. K.
Partner: UNT Libraries Government Documents Department

A portable gamma-ray spectrometer using compressed xenon

Description: An ionization chamber using compressed xenon has been designed and built for gamma-ray spectrometry. The device is based on signal measurement from a parallel plate detector, with the gas enclosure constructed specifically for packaging into a portable instrument; thus, appropriate engineering practices comprises two small containers that can be setup for operation in just a few minutes. Its sensitivity is 100 keV to over 1 MeV, with a resolution at 662 keV of 2.5% FWHM for uniform irradiation, and 2% FWHM for collimated irradiation, comparable to the best ever with compressed xenon. It also exhibits greater specificity that most scintillators, such as NaI. The device is insensitive to neutron damage and has a low power requirement.
Date: October 1, 1997
Creator: Mahler, G.J.; Yu, B.; Smith, G.C.; Kane, W.R. & Lemley, J.R.
Partner: UNT Libraries Government Documents Department

ATOMIC BEAM STUDIES IN THE RHIC H-JET POLARIMETER.

Description: The results of atomic beam production studies are presented. Improved cooling of the atoms before jet formation in the dissociator cold nozzle apparently reduces the atomic beam velocity spread and improves beam focusing conditions. A carefully designed sextupole separating (and focusing) magnet system takes advantage of the high brightness source. As a result a record beam intensity of a 12.4 {center_dot} 10{sup 16} atoms/s was obtained within 10 mm acceptance at the collision point. The results of the polarization dilution factor measurements (by the hydrogen molecules at the collision point) are also presented.
Date: January 28, 2005
Creator: MAKDISI,Y.; ZELENSKI,A.; GRAHAM,D.; KOKHANOVSKI,S.; MAHLER,G.; NASS,A. et al.
Partner: UNT Libraries Government Documents Department

ATOMIC BEAM POLARIZATION MEASUREMENT OF THE RHIC POLARIZED H-JET TARGET.

Description: The RHIC polarized H-Jet measures the polarization of the RHIC proton beam via elastic scattering off a nuclear polarized atomic hydrogen beam. The atomic beam is produced by a dissociator, a beam forming system and sextupole magnets. Nuclear polarization is achieved by exchanging occupation numbers of hyperfine states using high frequency transitions. The polarization was measured using a modified form of a Breit-Rabi polarimeter including focusing magnets and another set of high frequency transitions. The sampling of a large part of the beam and low noise electronics made it possible to measure the polarization to a high degree of accuracy in a very short time period (1 min). Using this system, we measured no depolarization of the atomic beam due to the RF fields of the bunched proton beam. Time-of-Flight measurements were done using a fast chopper and a QMA at the position of the RHIC interaction point to determine the areal density of the atomic beam seen by the RHIC beam.
Date: January 28, 2005
Creator: Makdisi, Y.; Nass, A.; Graham, D.; Kponou, A.; Mahler, G.; Meng, W. et al.
Partner: UNT Libraries Government Documents Department

POLARIZED HYDROGEN JET TARGET FOR MEASUREMENT OF RHIC PROTON BEAM POLARIZATION.

Description: The performance and unique features of the RHIC polarized jet target and our solutions to the important design constraints imposed on the jet by the RHIC environment are described. The target polarization and thickness were measured to be 0.924 {+-} 2% and 1.3 {+-} 0.2 x 10{sup 12} atoms/cm{sup 2} respectively.
Date: January 28, 2005
Creator: MAKDISI,Y.; WISE,T.; CHAPMAN,M.; GRAHAM,D.; KPONOU,A.; MAHLER,G. et al.
Partner: UNT Libraries Government Documents Department

UNIQUE FEATURES IN MAGNET DESIGNS FOR R AND D ENERGY RECOVERY LINAC AT BNL.

Description: In this paper we describe the unique features and analysis techniques used on the magnets for a R&D Energy Recovery Linac (ERL) [1] under construction at the Collider Accelerator Department at BNL. The R&D ERL serves as a test-bed for future BNL ERLs, such as an electron-cooler-ERL at RHIC [2] and a future 20 GeV ERL electron-hadron at eRHIC [3]. Here we present select designs of various dipole and quadruple magnets which are used in Z-bend merging systems [4] and the returning loop, 3-D simulations of the fields in aforementioned magnets, particle tracking analysis, and the magnet's influence on beam parameters. We discuss an unconventional method of setting requirements on the quality of magnetic field and transferring them into measurable parameters as well as into manufacturing tolerances. We compare selected simulation with results of magnetic measurements. A 20 MeV R&D ERL (Fig. 1) is in an advanced phase of construction at the Collider-Accelerator Department at BNL, with commissioning planned for early 2009. In the R&D ERL, an electron beam is generated in a 2 MeV superconducting RF photo-gun, next is accelerated to 20 MeV in a 5 cell SRF linac, subsequently passed through a return loop, then decelerated to 2 MeV in the SRF linac, and finally is sent to a beam dump. The lattice of the R&D ERL is designed with a large degree of flexibility to enable the covering of a vast operational parameter space: from non-achromatic lattices to achromatic with positive, zero and negative R56 parameter. It also allows for large range tunability of Rlz and lattice RS4 parameters (which are important for transverse beam-break-up instability). Further details of the R&D ERL can be found elsewhere in these proceedings [5]. The return loop magnets are of traditional design with the following exceptions: (a) The bending radius of ...
Date: June 25, 2007
Creator: MENG,W.; JAIN, A.; GANETIS, G.; KAYRAN, D.; LITVINENKO, V.N.; LONGO, C. et al.
Partner: UNT Libraries Government Documents Department

AN OVERVIEW OF THE SNS ACCELERATOR MECHANICAL ENGINEERING.

Description: The Spallation Neutron Source (SNS*) is an accelerator-based neutron source currently nearing completion at Oak Ridge National Laboratory. When completed in 2006, the SNS will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. SNS is a collaborative effort between six U.S. Department of Energy national laboratories and offered a unique opportunity for the mechanical engineers to work with their peers from across the country. This paper presents an overview of the overall success of the collaboration concentrating on the accelerator ring mechanical engineering along with some discussion regarding the relative merits of such a collaborative approach. Also presented are a status of the mechanical engineering installation and a review of the associated installation costs.
Date: June 23, 2006
Creator: HSEUH, H.; LUDWIG, H.; MAHLER, G.; PAI, C.; PEARSON, C.; RANK, J. et al.
Partner: UNT Libraries Government Documents Department

A FLYING WIRE SYSTEM IN THE AGS.

Description: As the AGS prepares to serve as the injector for RHIC, monitoring and control of the beam transverse emittance become a major and important topic. Before the installation of the flying wire system, the emittance was measured with ionization profile monitors in the AGS, which require correction for space charge effects. It is desirable to have a second means of measuring profile that is less depend on intensity. A flying wire system has been installed in the AGS recently to perform this task. This paper discusses the hardware and software setup and the capabilities of the system.
Date: March 29, 1999
Creator: HUANG,H.; BUXTON,W.; MAHLER,G.; MARUSIC,A.; ROSER,T.; SMITH,G. et al.
Partner: UNT Libraries Government Documents Department

The dipole corrector magnets for the RHIC fast global orbit feedback system

Description: The recently completed RHIC fast global orbit feedback system uses 24 small 'window-frame' horizontal dipole correctors. Space limitations dictated a very compact design. The magnetic design and modelling of these laminated yoke magnets is described as well as the mechanical implementation, coil winding, vacuum impregnation, etc. Test procedures to determine the field quality and frequency response are described. The results of these measurements are presented and discussed. A small fringe field from each magnet, overlapping the opposite RHIC ring, is compensated by a correction winding placed on the opposite ring's magnet and connected in series with the main winding of the first one. Results from measurements of this compensation scheme are shown and discussed.
Date: March 28, 2011
Creator: Thieberger, P.; Arnold, L.; Folz, C.; Hulsart, R.; Jain, A.; Karl, R. et al.
Partner: UNT Libraries Government Documents Department

BNL 703 MHz SRF cryomodule demonstration

Description: This paper will present the preliminary results of the testing of the 703 MHz SRF cryomodule designed for use in the ampere class ERL under construction at Brookhaven National Laboratory. The preliminary cavity tests, carried out at Thomas Jefferson Laboratory, demonstrated cavity performance of 20 MV/m with a Qo of 1 x 10{sup 10}, results we expect to reproduce in the horizontal configuration. This test of the entire string assembly will allow us to evaluate all of the additional cryomodule components not previously tested in the VTA and will prepare us for our next milestone test which will be delivery of electrons from our injector through the cryomodule to the beam dump. This will also be the first demonstration of an accelerating cavity designed for use in an ampere class ERL, a key development which holds great promise for future machines.
Date: May 4, 2009
Creator: Burrill,A.; Ben-Zvi, I.; Calaga, R.; Dalesio, L.; Dottavio, T.; Gassner, D. et al.
Partner: UNT Libraries Government Documents Department

COMPACT CdZnTe-BASED GAMMA CAMERA FOR PROSTATE CANCER IMAGING

Description: In this paper, we discuss the design of a compact gamma camera for high-resolution prostate cancer imaging using Cadmium Zinc Telluride (CdZnTe or CZT) radiation detectors. Prostate cancer is a common disease in men. Nowadays, a blood test measuring the level of prostate specific antigen (PSA) is widely used for screening for the disease in males over 50, followed by (ultrasound) imaging-guided biopsy. However, PSA tests have a high false-positive rate and ultrasound-guided biopsy has a high likelihood of missing small cancerous tissues. Commercial methods of nuclear medical imaging, e.g. PET and SPECT, can functionally image the organs, and potentially find cancer tissues at early stages, but their applications in diagnosing prostate cancer has been limited by the smallness of the prostate gland and the long working distance between the organ and the detectors comprising these imaging systems. CZT is a semiconductor material with wide band-gap and relatively high electron mobility, and thus can operate at room temperature without additional cooling. CZT detectors are photon-electron direct-conversion devices, thus offering high energy-resolution in detecting gamma rays, enabling energy-resolved imaging, and reducing the background of Compton-scattering events. In addition, CZT material has high stopping power for gamma rays; for medical imaging, a few-mm-thick CZT material provides adequate detection efficiency for many SPECT radiotracers. Because of these advantages, CZT detectors are becoming popular for several SPECT medical-imaging applications. Most recently, we designed a compact gamma camera using CZT detectors coupled to an application-specific-integrated-circuit (ASIC). This camera functions as a trans-rectal probe to image the prostate gland from a distance of only 1-5 cm, thus offering higher detection efficiency and higher spatial resolution. Hence, it potentially can detect prostate cancers at their early stages. The performance tests of this camera have been completed. The results show better than 6-mm resolution at a distance of ...
Date: October 23, 2011
Creator: CUI, Y.; LALL, T.; TSUI, B.; YU, J.; MAHLER, G.; BOLOTNIKOV, A. et al.
Partner: UNT Libraries Government Documents Department