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We describe the various steps in calculating the thermal stress in the RHIC beam dump windows, and list the maximum beam intensities for various species and energies to ensure safe operation of the beam dump. Furthermore, we propose a possible upgrade scenario that would increase these limits.

The objective of this note is to (once again) explore the AGS 'ORM' (orbit response matrix) data taken (by Operations) early during the 2007 run with an AGS bare machine and gold beam. Indeed the present motivation is to extract as much information about the AGS inherent transverse coupling as possible - from general arguments and the copious ORM data. And taking this one step further, (though not accomplished yet) the goal really should be to tell the model how to describe this coupling. 'Bare' as used here means the AGS with no quadrupole, sextupole or octupole magnets powered. Only the main (combined-function) magnet string and dipole bumps necessary to optimize beam survival are powered. 'ORM data' means the systematic recording of the equilibrium orbit beam position monitor response to powering individual dipole corrector magnets. The 'matrix' results from looking at the effect of each of the (12 superperiods X 4 dipoles per superperiod) 'kicks' on each of the (12 X 6) pick up electrodes (pues) in each transverse plane. So then we have two (48 X 72) matrices of numbers from the ORM data. (Though 'pue' usually refers to the hardware in the vacuum chamber and 'bpm' to themore » beam position monitoring system, the two labels will be used casually here.) The exercise is carried out at two magnet rigidities, injection (AGS field {approx}434 Gauss) and extraction to RHIC ({approx}9730 Gauss), - a ratio of rigidities of about 22.4. Since we stick with a bare machine, we are also stuck with the bare tunes which means the tunes are rather close together and near 8.75. Injection: (h,v) {approx} (8.73, 8.76).« less

Localized losses of gold beam in the AGS during RHIC Run 8 produced vacuum leaks which required the replacement of several vacuum chambers. A review of what happened and why was given by Leif Ahrens at the Run 8 Retreat. The following notes trace the subsequent development of clean dumping of gold beam on the beam dump in the J10 straight. The novel idea of stripping Au77+ ions in order to put them directly into the upstream face of the dump was introduced by Leif Ahrens and developed by all three of us. George Mahler made the actual stripping device and Dave Gassner developed its control. Leif Ahrens successfully commissioned the device with gold beam during Run 10. The reader may find it helpful to first view the figures herein and then refer to the text for details.

Effects of the Booster vertical scraping on the RHIC beam polarization, the RHIC beam emittance, and on the Booster to AGS transfer efficiency and AGS transmission as well, are further studied. In [1], the strong dependence of the RHIC beam polarization and emittance on bunch intensity in proton run 2008 (pp08) is compared with the proton run 2006 (pp06), where the dependence is much weaker. The setting in the AGS Booster, mainly the vertical scraping, is suspected to having played a role in the different patterns in the two runs. In this note, we further study the effects of the Booster vertical scraping on the RHIC beam polarization, and on the RHIC beam emittance as well. With the improvement of the RHIC bunch intensity in mind, the Booster scraping effects on the Booster to AGS transfer (BtA) efficiency and the AGS transmission are also studied. For simplicity and to be more useful, only the RHIC fills after the one-week shutdown in pp06 and the fills using the AGS User 2 in pp08 are shown. For these fills, the machine settings in AGS are similar in pp06 and pp08 runs. Furthermore, this setting might be used for next polarized proton run,more » at least at the beginning of the run.« less

During Run‐8, the Relativistic Heavy Ion Collider (RHIC) provided collisions of spin‐polarized proton beams at two interaction regions. Physics data were taken with vertical orientation of the beam polarization, which in the “Yellow” RHIC ring was significantly lower than in previous years. We present recent developments and improvements as well as the luminosity and polarization performance achieved during Run‐8, and we discuss possible causes of the not as high as previously achieved polarization performance of the “Yellow” ring.

As part of the preparation for the Proton Interrogation Experiment, we have calculated the beam optics for the transport of 4 GeV protons, from the AGS extraction point, to the 'Cross-Section Target Wheel 1' and to the 'Proton Interrogation Target'. In this technical note we present three possible beam-transports each corresponding to a particular Fast Extracted Beam W B setup of the AGS. In addition we present results on the effect of the atmospheric air, (which fills the drift space of the last 100 [m] of the transport line), on the size of the beam, at two locations along the drift space, one location at the middle of the drift space and the other at the end where the 'Proton Interrogation Target' is placed. All the beam transports mentioned above require the removal of the WD1 dipole magnet, which is the first magnet of the W-line, because it acts as a limiting beam aperture, and the magnet is not used in the beam transport. An alternative solution of a beam transport, which does not require the removal of the WD1 magnet, is also presented. In this solution, which models the transport line using the TURTLE computer code[7], the vertical beammore » sizes at the location of the WD1 magnet is minimized to allow 'lossless' beam transport at the location of the WD1 magnet. A similar solution, but using a MAD model of the line, is also presented.« less

Follow up on BtA multiwire beam measurements taken during the 2008 polarized proton run has led to a number of better understandings (for the author) associated with the beam instrumentation involved. This history will be reviewed--some 'beam-based' results noted--and the present state of the application for these monitors described. The BtA multiwire system seems to be fundamentally an excellent diagnostic for allowing us to get the BtA line well under control in a defendable way. When beam is available in BtA, carrying out some systematic measurements with the system can get us there.

Dual partial snake scheme has provided polarized proton beams with 1.5 times 1011 intensity and 65% polarization for the relativistic heavy ion collider (RHIC) spin program. To overcome the residual polarization loss due to horizontal resonances in the Brookhaven alternating gradient synchrotron (AGS), a new string of quadrupoles have been added. The horizontal tune can then be set in the spin tune gap generated by the two partial snakes, such that horizontal resonances can also be avoided. This paper presents the accelerator setup and preliminary results.

The present AGS injection kickers at A5 location were designed for 1.5 GeV proton injection. Recent high intensity runs have pushed the transfer kinetic energy to 1.94 GeV, but with an imperfect matching in transverse phase space. Space charge forces result in both fast and slow beam size growth and beam loss as the size exceeds the AGS aperture. A proposed increase in the AGS injection energy to 2 GeV with adequate kick strength would greatly reduce the beam losses making it possible increase the intensity from 70 TP (701012protons/s) to 100 TP. R&D studies are being undertaken by TRIUMF, in collaboration with BNL, to design two new kicker magnets for the AGS A10 location which will provide an additional deflection of 1.5 mrad for 2 GeV protons. TRIUMF has proposed a design for a 12.5 Ω transmission line kicker magnet with rise and fall times of 100 ns, 3% to 97%, and kick strength uniformity for protons of ± 3% over 90% of the aperture, powered by matched 12.5 Ω pulse-forming lines. This paper describes the present status of a prototype design including the results of detailed 2D and 3D electromagnetic modelling of a transmission line kicker magnet and PSpice time domain analysis of the magnetic kick strength.

In this paper we discuss, and study the feasibility of a method that may be used to measure the focusing properties of a magnet. This method may prove valuable when applied to “non_conventional” magnets that deviate from the usual dipole magnets or other multipole magnets (quadrupoles /sextupoles etc.) which are commonly used in a synchrotron or a beam line. In this category of “non_conventional” magnets, fall special magnets, which come under the name “Snakes”, which are being used in synchrotron accelerators[1,2,3,4] to introduce artificial spin resonances to help overcome the intrinsic and/or imperfection spin resonances which appear during the acceleration of polarized beams. This method of measuring the focusing properties of a magnet requires the use of “low energy” and “high rigidity” heavy-ions which may be obtained from the BNL Tandem accelerator. In brief the method consists on, injecting “narrow_beamlets” of heavy ions into a magnet and measuring the coordinates, of these “narrow_beamlets”, at the entrance and exit of the magnet. From the measurement of the coordinates of the “narrow_beamlets” we can deduce information on the first order transfer matrix elements (R matrix) and higher order matrix elements that define the focusing properties of the magnet.

Preliminary results from the ’03 RHIC Proton Spin Run on the spin dependence in the elastic scatterring of polarized protons off a carbon target at very low momentum transfer (0.005 < |t| < 0.05 GeV2/c2) are presented and discussed. Proton polarimeters based on this process are used in RHIC and AGS to measure reliably and in very short times the polarization of the proton beams. Polarimetry results from the just completed RHIC polarized proton run are also presented.

During the acceleration cycle of the AGS synchrotron, eddy currents are generated within the walls of the vacuum chambers of the AGS main magnets. The vacuum chambers have elliptical cross section, are made of inconel material with a wall thickness of 2 mm and are placed within the gap of the combined-function main magnets of the AGS synchrotron. The generation of the eddy currents in the walls of the vacuum chambers, create various magnetic multipoles, which affect the optics of the AGS machine. In this report these magnetic multipoles are calculated for various time interval starting at the acceleration cycle, where the magnetic field of the main magnet is /spl sim/0.1 T, and ending before the beam extraction process, where the magnetic field of the main magnet is almost constant at /spl sim/1.1 T. The calculations show that the magnetic multipoles generated by the eddy-currents affect the optics of the AGS synchrotron during the acceleration cycle and in particular at low magnetic fields of the main magnet. Their effect is too weak to affect the optics of the AGS machine during beam extraction at the nominal energies.

In the fall of 1995, we successfully completed a major milestone in the RHIC (Relativistic Heavy Ion Collider) project: the first beam test of the AGS (Alternating Gradient Synchrotron) to RHIC (ATR) transfer line. The ATR serves as a test bed for the new RHIC control system. This transfer line is highly instrumented, with several types of instrumentation for characterizing the extracted beam from AGS and for matching the beam into RHIC. We describe the design and performance of ATR with gold ions with an eye to reaching the design criteria for RHIC operation, both in beam quality and controls.

AGS beam losses at transition are now tolerable ({lt}5%), but as the present improvement plans are implemented and the intensity is increased, new mechanisms will become important and the losses will increase. This Note describes studies directed towards minimizing these losses. Werner Hardt has studied these losses at the CERN PS. In particular, he found that by sharply reducing the time spent going through transition he could reduce the losses. Hardt visited Brookhaven in early June, 1986, in order to help us better understand the AGS. As a result of work inspired by his visit, we now believe that intensities of {approximately}5x10{sup 13} circulating protons are attainable in the AGS without significant losses at transition.