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Effect of synchrotron radiation in the proposed 4 GeV Argonne microtron

Description: Synchrotron radiation in the sector magnets of the 4-GeV microtron designed at the Argonne National Laboratory produces a small but noticeable distortion of the closed orbits of the system and a very-significant growth of the horizontal and longitudinal phase-space emittances. Because of the small apertures in the three 25-meter linacs, it is important that the expected growth of the beam be calculated as accurately as possible. For this reason, a computer program has been written which follows the motions of individual electrons in the four dimensional horizontal and longitudinal phase space as they are accelerated in the system. As the electrons go through the sector magnets, they emit quanta at random with randomly chosen energies. The final results show 63% emittance (area ..pi..) values of 0.15 mm mrad and 630 keV degrees for the horizontal and longitudinal phase spaces, respectively. The 99% values are about 4.6 times larger.
Date: January 1, 1983
Creator: Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Improvement of the dynamic aperture in Chasman Green lattice design light source storage rings

Description: The Chasman-Green half cell illustrates a typical electron or positron storage ring lattice specifically designed for photon beams from undulators and wigglers located in each dispersion-free straight section. The need for a small particle beam emittance requires that the horizontal phase advance per cell should be in the neighborhood of 0.9 x 2 . Necessary chromaticity correcting sextupoles, S/sub D/ and S/sub F/, located in the dispersion straight section introduce non-linear perturbations which limit the dynamic aperture because of amplitude dependent tune shifts. Two families of sextupoles, S1 and S2, can be introduced into the dispersion-free region to moderate the more harmful effects of S/sub D/ and S/sub F/. The nature of the perturbations are discussed and some guidelines for the adjustment of S1 and S2 sextupoles are given.
Date: January 1, 1987
Creator: Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Use of the ''MURA'' transformation to generate the fields and calculate the motion of protons in the designed Argonne Mini-ASPUN FFAG Spiral Sector Accelerator

Description: As a long range goal for the production of high intensity neutrons, Argonne National Laboratory has proposed the construction of a 1.5 GeV FFAG Spiral Sector Accelerator called ASPUN. The 500-MeV injector for this proposed accelerator is a smaller FFAG Spiral Sector Accelerator named Mini-ASPUN. Until such a time as the larger machine could be built, it was planned that Mini-ASPUN would replace the present RCS now being used for the IPNS program at Argonne. In order to obtain an accurate estimation of the orbits and betatron oscillations in such a machine, it is necessary that realistic field values be used in the equations of motion. Obtaining these fields from 3-dimensional relaxation calculations is both time consuming and costly. However, because of the required scaling of the machine, the field-generating potential of three variables can be separated into a known function of the radius and a function of two variables. The second order differential equation satisfied by this function can be solved by ordinary relaxation methods. The fields generated from a mesh of values for this function will be accurate except for the extreme inside and outside orbits, which will be affected by the necessary termination of the inside and outside ends of the magnet. 2 refs., 4 figs., 1 tab.
Date: May 13, 1985
Creator: Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Revised lattice for the APS storage ring

Description: As a result of more detailed engineering studies of vacuum chamber components and related accelerator physics studies, the circumference of the APS storage ring is increased by 44 m to a value of 1104 m. The increase is 1.1 m for each of the 40 sectors. The insertion region straight section is lengthened by 0.52 m to 6.72 m. This allows full 20-cm vacuum chamber transition sections leading into and out of the 5.2-m insertion devices. Computer studies using TBCI and MAFIA-T3 have indicated that 20-cm-long transition regions reduce the transverse coupling impedance to an Acceptable low value. The results for 10-cm transition length were marginal.
Date: August 1, 1989
Creator: Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Theoretical estimation of the dynamic aperture for a Chasman-Green lattice

Description: A comparison between the predicted stability region and the results of tracking for the 7-GeV Advanced Photon Source CDR lattice is given. The tracking results are obtained by searching for the limit of stability in N{sub y} for a fixed value for N{sub x}. (Negative N{sub x} is understood to mean cos {phi}{sub xo} = {minus}1.) The limits of the stable region for this lattice are caused by the chromaticity correcting sextupoles and the predominance of the integral resonance for v{sub x} = 0.88 per period.
Date: November 1, 1988
Creator: Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

A positron accumulator ring for APS

Description: The new positron injection scheme is as follows. The cycle rate of the injector synchrotron is increased to 2 Hz. During 0.4 sec of each 0.5-sec synchrotron cycle, 24 linac pulses are injected into the horizontal phase space of the PAR at a 60-Hz rate. Each injected pulse occupies about 1/3 of the circumference of the accumulator ring. After 0.1 sec for longitudinal damping, the single accumulated bunch is transferred into one of the 352.96-MHz buckets of the injector synchrotron RF system. This single bunch is accelerated to 7 GeV and transferred into the storage ring while the PAR accumulates the next bunch of positrons. The injector synchrotron requires only the one high-frequency RF system.
Date: March 1, 1988
Creator: Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Determination of transverse phase-space and momentum error from size measurements along the 50-MeV H/sup -/ RCS injection line

Description: The 50-MeV H/sup -/ injection line for the RCS at Argonne National Laboratory has 16 quadrupole and eight bending magnets. Horizontal and vertical profiles can be obtained at 12 wire scanner positions. Size information from these profiles can be used to determine the three ellipses parameters in each plane required to describe the transverse phase space. These locations that have dispersion permit the momentum error to be used as a fourth fitting parameter. The assumed accuracy of the size measurements provides an error matrix that predicts the rms errors of the fitted parameters.
Date: January 1, 1981
Creator: Cho, Y.; Crosbie, E.A. & Takeda, H.
Partner: UNT Libraries Government Documents Department

Lattice considerations for a tau-charm factory

Description: The magnet lattice appropriate for a tau-charm factory had been studied extensively. Here we discuss two possible simplifying features which make the design, construction, and operation of the machine simpler without sacrificing performance. These two features may be characterized and identified as (a) luminosity optimization in the ``monochromatic`` mode, and (b) chromaticity correction with sextupoles only in the arcs.
Date: June 1, 1995
Creator: Teng, L.C. & Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Retuning the APS storage ring for better chromaticity correction.

Description: When the APS storage ring was retuned to provide smaller {beta}{sub y} values in the insertion straight sections, it was necessary to increase the vertical tune by at least two units. Since the design values for the horizontal and vertical tunes are 35.22 and 16.30, respectively, this put the tunes dangerously close to the sextupole 2v{sub y}-v{sub x} coupling resonance. The large injection horizontal oscillations could couple to the vertical plane and exceed the 5-mm vertical apertures that exist in some of the insertion straight sections. To avoid this resonance, the vertical tune was raised beyond the resonance to 19.30. The result was a reduction in the ability of the chromaticity sextuples to correct the chromaticity. Recent investigation has shown that the chromaticity correction capability of the sextuples can be greatly increased by a modest increase in the horizontal tune. Increasing the horizontal tune by one unit and reducing the vertical tune by three units produces a lattice with better chromaticity control while maintaining an acceptable dynamic aperture.
Date: September 11, 1999
Creator: Chae, Y.-C. & Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Preliminary study of insertion device effect on dynamic aperture using RACETRACK

Description: We studied the effects of an insertion device (ID) on the dynamic aperture using the new version of RACETRACK. We found that the nonlinear effect of the ID is the dominant effect on the dynamic aperture reduction compared to the other multipole errors which exist in the otherwise ideal lattice. The previous study of dynamic aperture was based on the assumption that the effect of the fast oscillating terms in L. Smith`s Hamiltonian is small, and hence can be neglected in the simulation. The remarkable agreement between the previous study and the current results using RACETRACK, including all effects of the fast oscillating terms, justified those assumptions at least for the APS ring.
Date: May 8, 1992
Creator: Chae, Yong-chul & Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Measurement of A and A/sub nn/ in p + p. -->. p + p at 6 GeV/c

Description: Previous measurements of the 6 GeV/c p - p elastic scattering rates have been extended with beam and target polarizations normal to the scattering plane. Improvements to the measuring technique include additional momentum resolution added to the recoil arm and increased solid angle resulting from two-element hodoscopes. Beam intensity was increased by a factor of 3 and additional shielding was installed. Along with the usual statistical uncertainty and errors in measurement of the target polarization, a term was added in quadrature due to a systematic difference between target and beam asymmetries (A/sub T/ and A/sub B/). (GHT)
Date: January 1, 1980
Creator: Crosbie, E.A.; Ratner, L.G. & Schultz, P.F.
Partner: UNT Libraries Government Documents Department

The positron accumulator ring for the APS

Description: The Positron Accumulator Ring (PAR) is designed to accumulate and damp positrons from the 450-MeV linac during the 0.5-s cycle time of the injector synchrotron for the APS 7-GeV storage ring. During 0.4 s of each synchrotron cycle, up to 24 linac pulses are injected into the horizontal phase space of the PAR at a 60-Hz rate. Each injected pulse occupies about 1.3 of the circumference of the accumulator ring. After 0.1 s for longitudinal damping, the single accumulated bunch is transferred to one of the 353-MHz buckets of the injector synchrotron RF system. The bunch is accelerated to 7 GeV and transferred to the storage ring, while the PAR accumulates the next bunch of positrons. 2 refs., 3 figs., 2 tabs.
Date: January 1, 1989
Creator: Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

1500-MeV fixed-field alternating-gradient synchrotron for a pulsed-spallation neutron source

Description: The first conceptual design of the FFAG for ASPUN was an 1100-MeV, 20-sector machine with an injection radius of 17.5 m and an extraction radius of 18.75 m. The conceptual design currently under study has a higher extraction energy, a larger average radius, but still has 20 sectors. The current interest in higher extraction energy is stimulated by calculations that indicate that the useful neutron production per incident proton is still increasing proportionally up to 1500 MeV. The larger radius also matches existing buildings at Argonne that could be made available for the facility. 11 refs., 4 figs., 3 tabs.
Date: January 1, 1985
Creator: Kustom, R.L.; Khoe, T.K. & Crosbie, E.A.
Partner: UNT Libraries Government Documents Department

Achromatic lattice comparison for light sources

Description: The next generation of synchrotron light sources are being designed to support a large number of undulators and require long dispersion-free insertion regions. With less demand for radiation from the dipole magnets, the storage ring cost per undulator beam can be reduced by decreasing the number of dipole magnets and increasing the number of dispersion free straight sections. The two simplest achromatic lattices are the Chasman-Green or double-bend achromatic (DBA) and the three-bend achromat (TBA). The DBA in its simplest form consists of a single horizontally-focussing quadrupole between the two dipole magnets. Since this quadrupole strength is fixed by the achromatic condition, the natural emittance (/var epsilon//sub n/) may vary as the beta functions in the insertion region (IR) are varied. The expanded Chasman-Green (also DBA) uses multiple quadrupoles in the dispersive section to provide emittance control independent of the beta functions in the IR. Although this provides flexibility in the ID beta functions, the horizontal phase advance is constrained to /phi/ /approx equal/ 180/degree/ between approximately the centers of the dipole magnets. If small /var epsilon//sub n/ is required, the horizontal phase advance between the dipoles will be near one and the lattice properties will be dominated by this systematic resonance. The TBA lattice places a third dipole between the DBA dipoles, eliminating the 180/degree/ horizontal phase advance constraint. However, the requirement of small /var epsilon//sub n/ limits the range of tune, since /mu//sub x/ /approx equal/ 1.29 in the dipoles alone for /var epsilon//sub n/ near its minimum value. The minimum emittance is five times smaller for the TBA than for the DBA with the same number of periods and, therefore, its phase advance can be relaxed more than the DBA for the same natural emittance. 5 refs., 4 figs., 1 tab.
Date: January 1, 1988
Creator: Kramer, S.L.; Crosbie, E.A. & Cho, Y.
Partner: UNT Libraries Government Documents Department

Argonne Tau-charm factory collider design study

Description: The design approach and design principles for a Tau-charm Factory at Argonne were studied. These studies led to a set of preliminary parameters and tentative component features as presented in this paper.
Date: December 1, 1995
Creator: Teng, L.C.; Crosbie, E.A. & Norem, J.
Partner: UNT Libraries Government Documents Department

Vacuum chamber thermal protection for the APS (Advanced Photon Source)

Description: The addition of undulators and wigglers into synchrotron storage rings created new problems in terms of protecting the integrity of the ring vacuum chamber. If the photon beam from these devices were missteered into striking an inadequately cooled section of the storage ring vacuum chamber, the structural strength might be reduced sufficiently that the vacuum envelope could be penetrated, resulting in long downtime of the storage ring. The new generation of high-energy synchrotron light sources will produce photon beams of such high power density that cooling of the vacuum chamber will not prevent a potential penetration of the vacuum envelope, and other methods of preventing this occurrence will be required. Since active methods will be used to ensure that the beams are delivered to beam lines for users during normal operation, there is a need for passive protection methods during non-routine operation, such as turning on new beam lines, injection, etc., when the active systems may be disabled. In addition, the passive methods could prevent the problem from arising and provide the rapid time response necessary for the highest power beams, a property that might not be easily and reliably provided by active methods during the early operation of these machines. This paper summarizes the results of a task group that studied the problem and outlines passive methods of protection for the Advanced Photon Source (APS). 2 refs., 3 figs., 1 tab.
Date: January 1, 1989
Creator: Kramer, S.L.; Crosbie, E.A.; Kim, S.; Wehrle, R. & Yoon, M.
Partner: UNT Libraries Government Documents Department

High energy polarized deuterons at the Argonne National Laboratory zero gradient synchrotron

Description: Modifications made on the ZGS to allow the acceleration of polarized deuterons and the operational experiences with the first production run with this beam are described.
Date: January 1, 1979
Creator: Parker, E.F.; Brandeberry, F.E.; Crosbie, E.A.; Knott, M.J.; Potts, C.W.; Ratner, L.C. et al.
Partner: UNT Libraries Government Documents Department

The FEL development at the Advanced Photon Source.

Description: Construction of a single-pass free-electron laser (FEL) based on the self-amplified spontaneous emission (SASE) mode of operation is nearing completion at the Advanced Photon Source (APS) with initial experiments imminent. The APS SASE FEL is a proof-of-principle fourth-generation light source. As of January 1999 the undulator hall, end-station building, necessary transfer lines, electron and optical diagnostics, injectors, and initial undulatory have been constructed and, with the exception of the undulatory, installed. All preliminary code development and simulations have also been completed. The undulator hall is now ready to accept first beam for characterization of the output radiation. It is the project goal to push towards fill FEL saturation, initially in the visible, but ultimately to W and VUV, wavelengths.
Date: March 15, 1999
Creator: Arnold, N. D.; Benson, C.; Berg, S.; Berg, W.; Biedron, S. G.; Chae, Y. C. et al.
Partner: UNT Libraries Government Documents Department