17 Matching Results

Search Results

Advanced search parameters have been applied.

New magnet pole shape for isochronous cyclotrons

Description: A new design has been developed for shaping pole tips to produce the radially increasing fields required for isochronous cyclotrons. The conventional solid hill poles are replaced by poles mounted over a small secondary gap which tapers radially from maximum at the magnet edge to zero near the center. Field measurements with a model magnet and calculations with the code TRIM show an increase in field at the edge of the magnet without the usual corresponding large increase in fringing, and a radial field shape more nearly field independent than for conventional hills. The flying hills have several advantages for variable energy multiparticle cyclotrons: (1) a large reduction in the power dissipated by isochronizing trim coils; (2) a more constant shape and magnitude flutter factor, eliminating flutter coils and increasing the operating range; and (3) a sharper fall-off of the fringe field, simplifying beam extraction.
Date: January 1, 1981
Creator: Thorn, C.E.; Chasman, C. & Baltz, A.J.
Partner: UNT Libraries Government Documents Department

Spectrometer coupled to an electron storage ring for tagging laser backscattered gamma rays

Description: A spectrometer has been designed to momentum analyze electrons, from the 2.5 to 3.0 GeV x-ray storage ring of the National Synchrotron Light Source at Brookhaven National Laboratory, that have lost energy from the production of high energy ..gamma..-rays by Compton scattering of laser light. The electrons detected in the focal plane will provide a tag for the backscattered ..gamma..-rays, determining their energy (to 2.3 MeV), and timing. This design utilizes the fact that, due to kinematics, the Compton scattered electrons have a transverse phase space negligibly different from that of the stored beam. It is constrained by the requirement of not altering any of the existing elements of the storage ring. In particular, no structures or fields interfere with the large aperture of the storage ring that is required for loading the ring.
Date: January 1, 1982
Creator: Thorn, C.E.; LeVine, M.J. & Sandorfi, A.M.
Partner: UNT Libraries Government Documents Department

Charged-pion spectrometer for the BNL gamma-ray-beam facility

Description: The (..gamma..,..pi../sup +-/) studies planned for the BNL Gamma Ray Beam Facility necessitate the detection of charged pions in the energy range 25 < T/sub pi/ < 150 MeV with a modest resolving power to match the photon beam energy resolution (27 MeV). The solid angle must be as large as possible, and the total path length must be as short as possible to minimize the losses due to pion decay. (The mean lifetime corresponds to L = 4.87 m for T/sub pi/ = 25 MeV). Finally, a means must be provided to reject pion decay products reaching the focal plane. A design for such a charged-pion spectrometer is presented. This design utilizes existing large aperture magnetic elements, and provides a momentum resolution of 0.68% at a solid angle of 50 msr, over a momentum range of 10%.
Date: January 1, 1982
Creator: LeVine, M.J.; Thorn, C.E. & Sandorfi, A.M.
Partner: UNT Libraries Government Documents Department

Spiral design and beam dynamics for a variable energy cyclotron

Description: Beam-orbit studies were performed for the conversion of the SREL synchrocyclotron magnet for use as a room temperature, multiparticle, isochronous cyclotron. Based on model magnet measurements of field profiles for 8 to 23/sup 0/K gauss hill fields, a four sector spiral pole tip design has been realized which allows all isotope species of heavy ion beams to be accelerated to required final energies. The total spiral angle of 38/sup 0/ allows injection of the beams from the MP tandem into the cyclotron through a valley. The two valey RF system of 140 kV peak accelerates beams on harmonic numbers 2, 3, 4, 6 and 10 at 14 to 21 MHz. Computer calculations indicated acceptable ..nu../sub z/, ..nu../sub r/ and phase space beam characteristics and passing of resonances for typical beams considered: /sup 16/O at 8 and 150 MeV/amu, /sup 60/Ni at 100 MeV/amu and /sup 238/U at 2.5 and 16 MeV/amu. Single turn extraction is achieved with electrostatic deflection.
Date: January 1, 1981
Creator: Baltz, A.J.; Chasman, C. & Thorn, C.E.
Partner: UNT Libraries Government Documents Department

pi. /sup 0/ spectrometer for photopion production studies

Description: One of the first experimental programs to be carried out with the BNL Gamma Ray Beam will be a study of (..gamma..,..pi../sup 0/). We present here a discussion of existing ..pi../sup 0/ spectrometers and two new designs which, for the ..pi../sup 0/ energy range of interest for this program, are superior to existing designs.
Date: January 1, 1982
Creator: LeVine, M.J.; Sandorfi, A.M. & Thorn, C.E.
Partner: UNT Libraries Government Documents Department

High-energy gamma-ray beams from Compton-backscattered laser light

Description: Collisions of light photons with relativistic electrons have previously been used to produce polarized ..gamma..-ray beams with modest (-10%) resolution but relatively low intensity. In contrast, the LEGS project (Laser + Electron Gamma Source) at Brookhaven will produce a very high flux (>2 x 10/sup 7/ s/sup -1/) of background-free polarized ..gamma.. rays whose energy will be determined to a high accuracy (..delta..E = 2.3 MeV). Initially, 300(420)-MeV ..gamma.. rays will be produced by backscattering uv light from the new 2.5(3.0)-GeV X-ray storage ring of the National Synchrotron Light Source (NSLS). The LEGS facility will operate as one of many passive users of the NSLS. In a later stage of the project, a Free Electron Laser is expectred to extend the ..gamma..-ray energy up to 700 MeV.
Date: January 1, 1983
Creator: Sandorfi, A.M.; LeVine, M.J.; Thorn, C.E.; Giordano, G. & Matone, G.
Partner: UNT Libraries Government Documents Department

Brookhaven Medium-Energy Gamma-Ray Project

Description: Within the next year we hope to begin the construction of a facility that would provide intense beams of monochromatic and polarized photons with energies in the range of several hundreds of MeV. These ..gamma.. rays will be produced by Compton backscattering laser light from the electrons circulating in the 2.5 to 3.0 GeV X-RAY storage ring of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. Gamma rays up to 80 MeV in energy are produced by this mechanism at the LADON facility at Frascati. However, the techniques that will be used at Brookhaven to produce monoenergetic polarized ..gamma..-ray beams are fundamentally different than those employed at Frascati. In this paper we summarize the essential aspects and phases of development of the BNL facility.
Date: January 1, 1982
Creator: Sandorfi, A. M.; LeVine, M. J.; Thorn, C. E.; Giordano, G. & Matone, G.
Partner: UNT Libraries Government Documents Department

A Proposal to the Department of Energy for The Fabrication of a Very High Energy Polarized Gama Ray Beam Facility and A Program of Medium Energy Physics Research at The National Synchrotron Light Source

Description: This proposal requests support for the fabrication and operation of a modest facility that would provide relatively intense beams of monochromatic and polarized photons with energies in the range of several hundreds of MeV. These {gamma} rays would be produced by Compton backscattering laser light from the electrons circulating in the 2.5-3.0 GeV 'X-RAY' storage ring of the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The excellent emittance, phase space, and high current of this state-of-the-art storage ring will allow the production of 2 x 10{sup 7} {gamma} rays per second. These photons would be tagged by detecting the scattered electrons, thereby determining the energy to 2.7 MeV for all {gamma}-ray energies. The efficiency of this tagging procedure is 100% and the {gamma}-ray beam would be essentially background free. Tagging will also allow the flexibility of operating with a dynamic range as large as 200 MeV in photon energy while still preserving high resolution and polarization. These beams will permit a fruitful study of important questions in medium-energy nuclear physics. The initial goals of this program are to reach reliable operation with photon energies up to 300 MeV and to develop {gamma}-ray beams with energies up to about 500 MeV. To demonstrate reliable operation, a modest physics program is planned that, for the most part, utilizes existing magnets and detector systems but nonetheless addresses several important outstanding problems. Gamma ray beams of the versatility, intensity, energy, and resolution that can be achieved at this facility are not currently available at any other world facility either existing or under construction. Furthermore, the proposed program would produce the first intense source of medium-energy {gamma} rays that are polarized. Because of the difficulties in producing such polarized beams, it is very unlikely that viable alternate sources can be developed in the ...
Date: September 1, 1982
Creator: Sandorfi, A.M.; LeVine, M.J.; Thorn, C.E.; Giordano, G. & Matone, G.
Partner: UNT Libraries Government Documents Department

Production of high-power CW UV by resonant frequency quadrupling of a Nd:YLF laser

Description: The authors have constructed a single ring to resonantly double an 18 watt Nd:YLF mode-locked laser and re-double the stored green to produce over 4 watts of power in the ultra-violet (UV). This laser is used to produce a beam of 470 MeV gamma-rays by Compton backscattering the laser beam from 2.8 GeV electrons stored in a synchrotron. Achieving high luminosity of the colliding beams requires very good mode quality and beam stability at the intersection point 22 meters from the laser. The ring consists of six mirrors, with two 25 cm radius of curvature mirrors enclosing each nonlinear crystal. The drive laser is a lamp-pumped Nd:YLF with a 50 ps bunch length at 76 MHz. A pointing stabilizer servo has been constructed as part of the infrared (IR) mode matching telescope. The IR to green conversion is accomplished in a 15 mm long non-critically phased matched LBO crystal located at a 40 micron waist, with an IR conversion efficiency of 70%. A stable, nearly diffraction limited UV beam of up to 4.2 watts is generated in a BBO crystal in the green storage ring. The output power is relatively independent of the efficiency of the LBO and BBO crystals. This fact makes it possible to reduce the amount of non-TEM{sub 00} modes created by walk-off of the UV by using relatively thin BBO crystals. At present, however, the lower bound on the BBO thickness is limited by the loss of conversion efficiency at high power.
Date: June 1999
Creator: Kuczewski, A. J.; Thorn, C. E.; Matone, G. & Giordano, G.
Partner: UNT Libraries Government Documents Department

Photodisintegration of the deuteron with polarized photons from LEGS

Description: An experiment is described which will measure the d(..gamma..,p) reaction with polarized photon beams from LEGS ranging in energy from 50 MeV to 530 MeV. The data will yield a new high-resolution high-statistics determination of the total unpolarized cross section, will isolate for the first time the polarization dependent part of the reaction, and will measure the photon-beam asymmetry with much higher resolution and accuracy than available from existing data. These will provide one of the most stringent tests for models of the nuclear force. In addition, high-resolution data will be taken with both linear and circularly-polarized ..gamma.. rays to search for the effects of bibaryons.
Date: January 1, 1985
Creator: Dowell, D.H.; Giordano, G.; Kistner, O.; Matone, G.; Sandorfi, A.M.; Schaerf, C. et al.
Partner: UNT Libraries Government Documents Department

Laser-Electron-Gamma-Source. Progress report, June 1984

Description: Construction of the Laser Electron Gamma Source (LEGS) began at Brookhaven in October 1983. When completed, the source will provide intense beams of monochromatic and polarized gamma rays with energies in the range of several hundreds of MeV. The planned layout of this facility with its experimental areas is shown. The gamma-ray beams will be produced by Compton backscattering uv laser light from the electrons circulating in the 2.5-3.0 GeV X-RAY storage ring of the National Synchrotron Light Source (NSLS) at BNL. The X-RAY ring is currently running with 50 mA at 1.7 GeV, and is expected to reach 2.5 GeV by November 1984. There is as yet no firm schedule for operation at 3.0 GeV, although some initial testing should be completed by the end of 1986. The availability of the 210-420 MeV LEGS beam will depend upon these 3 GeV studies.
Date: January 1, 1984
Creator: Dowell, D.H.; Giordano, G.; LeVine, M.J.; Matone, G.; Sandorfi, A.M.; Schaerf, C. et al.
Partner: UNT Libraries Government Documents Department

Photon scattering from the nucleon at LEGS (Laser Electron Gamma Source)

Description: The elastic scattering of linearly polarized photons is discussed as a means of measuring the E2/M1 mixing ratio in the excitation of the delta (1232) resonance. The crucial problem in extracting this quantity is the presence of interfering backgrounds. The difference of two scattering cross sections with different incident polarizations can be used to eliminate almost all of the background contributions. As a measure of the sensitivity of this method, such a cross section difference can exhibit a change of 2.4% for an E2/M1 ratio of one percent. The single correction of importance comes from the imaginary part of the fmm(1-) amplitude for magnetic dipole scattering through a spin 1/2 state. It is likely that this amplitude is strongly affected by the tail of the P11 (1470) Roper resonance, and new multipole analyses of photoproduction and Compton scattering, extending up to the energy of the P11, would help to control the errors on this term. 20 refs., 5 figs., 3 tabs.
Date: January 1, 1988
Creator: Sandorfi, A.M.; Blanpied, G.; Blecher, M.; Giordano, G.; Kistner, O.C.; Matone, G. et al.
Partner: UNT Libraries Government Documents Department

Laser-Electron-Gamma-Source. Progress report, July 1986

Description: When completed, the Laser Electron Gamma Source (LEGS) is expected to provide intense beams of monochromatic and polarized (circular or linear) gamma rays with energies up to 500 MeV. The gamma-ray beams will be produced by Compton backscattering uv laser light from the electrons circulating in a storage ring. Progress with installation of the facility is described, particularly the Ar-ion laser and tagging spectrometer. Tests of the tagging spectrometer coponents is reported, and a second laser is described for higher energy operation. Estimates are given of expected beam parameters. Experimental equipment for the planned research projects to be carried out at the LEGS facility is discussed. (LEW)
Date: July 1, 1986
Creator: Dowell, D.H.; Fineman, B.; Giordano, G.; Kistner, OC.; Matone, G.; Sandorfi, A.M. et al.
Partner: UNT Libraries Government Documents Department

Scattering of polarized photons at LEGS

Description: The Laser-Electron-Gamma-Source (LEGS) facility at Brookhaven National Laboratory is now coming into operation. This facility delivers intense, monochromatic beams of medium-energy gamma rays that are almost completely polarized (linear or circular), and this degree of freedom has altered the status of a number of important experiments from being impossible to now being merely difficult. In this lecture we will describe the key features of the LEGS facility, and discuss two elastic scattering experiments on the nucleon, one in the region of the first resonance which is sensitive to the E2/M1 mixing ratio in the delta, and the other below pion threshold which is sensitive to the nucleon polarizabilities. These will illustrate the unique potential of the polarization degree of freedom. 36 refs., 9 figs., 4 tabs.
Date: January 1, 1988
Creator: Sandorfi, A.M.; Blanpied, G.; Blecher, M.; Giordano, G.; Kistner, O.C.; Matone, G. et al.
Partner: UNT Libraries Government Documents Department

The E2 N[yields][Delta] transition from polarized Compton scattering

Description: Short communication.
Date: January 1, 1993
Creator: Sandorfi, A.M.; Caracappa, A.; Kistner, O.C.; Thorn, C.E. (Brookhaven National Lab., Upton, NY (United States)); Miceli, L. (Brookhaven National Lab., Upton, NY (United States) South Carolina Univ., Columbia, SC (United States). Dept. of Physics); Giordano, G. et al.
Partner: UNT Libraries Government Documents Department

A portable cryostat for the cold transfer of polarized solid HD targets: HDice-I

Description: A device has been developed with moveable liquid nitrogen and liquid helium volumes that is capable of reaching over two meters into the coldest regions of a cryostat or dilution refrigerator and reliably extracting or installing a target of solid, polarized hydrogen deuteride (HD). This Transfer Cryostat incorporates a cylindrical neodymium rare-earth magnet that is configured as a Halbach dipole, which is maintained at 77 K and produces a 0.1 T field around the HD target. Multiple layers provide a hermetic 77 K-shield as the device is used to maintain a target at 2 K during a transfer between cryostats. Tests with frozen-spin HD show negligible polarization loss for either H or D over typical transfer periods. Multiple target transfers with this apparatus have shown an overall reliability of about 95% per transfer, which is a significant improvement over earlier versions of the device.
Date: February 1, 2014
Creator: Bass, Christopher D.; Sandorfi, Andy M.; Bade, C.; Blecher, M.; Caracappa, A.; D'Angelo, A. et al.
Partner: UNT Libraries Government Documents Department