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M Bai,
L Ahrens,
I G Alekseev,
J Alessi,
E Courant,
A Drees,
W Fischer, C Gardner,
R Gill,
J Glenn, [......],
V Ptitsyn,
T Roser,
D Svirida,
T Satogata,
S Tepikian,
D Trbojevic,
N Tsoupas,
A Zelenski,
K Zeno,
S Y Zhang
[show abstract]
[hide abstract]
ABSTRACT: The Siberian snakes are powerful tools in preserving polarization in high energy accelerators has been demonstrated at the Brookhaven Relativistic Heavy Ion Collider (RHIC). Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the Siberian snakes also introduce a new set of depolarization resonances, i.e. snake resonances as first discoverd by Lee and Tepikian [1]. The intrinsic spin resonances above 100 GeV are about a factor of two stronger than those below 100 GeV which raises the challenge to preserve the polarization up to 250 GeV. In 2009, polarized protons collided for the first time at the RHIC design store energy of 250 GeV. This paper presents the experimental measurements of snake resonances at RHIC. The plan for avoiding these resonanances is also presented.
Journal of Physics Conference Series 05/2011; 295(1):012142.
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H Huang,
L A Ahrens,
M Bai,
K Brown,
E D Courant, C Gardner,
J W Glenn,
F Lin,
A U Luccio,
W W Mackay,
M Okamura,
V Ptitsyn,
T Roser,
J Takano,
S Tepikian,
N Tsoupas,
A Zelenski,
K Zeno
[show abstract]
[hide abstract]
ABSTRACT: Acceleration of polarized protons in the energy range of 5 to 25 GeV is challenging. In a medium energy accelerator, the depolarizing spin resonances are strong enough to cause significant polarization loss but full Siberian snakes cause intolerably large orbit excursions and are also not feasible since straight sections usually are too short. Recently, two helical partial Siberian snakes with double pitch design have been installed in the Brookhaven Alternating Gradient Synchrotron (AGS). With a careful setup of optics at injection and along the energy ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances otherwise encountered during acceleration to maintain a high intensity polarized beam in medium energy synchrotrons. The observation of partial snake resonances of higher than second order will also be described.
Physical Review Letters 11/2007; 99(15):154801. · 7.37 Impact Factor
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H. Huang,
L. Ahrens,
M. Bai,
K.A. Brown, C. Gardner,
J.W. Glenn,
F. Lin,
A.U. Luccio,
W.W. MacKay,
T. Roser,
S. Tepikian,
N. Tsoupas,
K. Yip,
K. Zeno
[show abstract]
[hide abstract]
ABSTRACT: Dual partial snake scheme has provided polarized proton beams with 1.5 times 10<sup>11</sup> 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.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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M. Bai,
L. Ahrens,
I.G. Alekseev,
J. Alessi,
J. Beebe-Wang,
M. Blaskiewicz,
A. Bravar,
J.M. Brennan,
K. Brown,
D. Bruno, [......],
D.N. Svirida,
D. Trbojevic,
N. Tsoupas,
J. Tuozzolo,
M. Wilinski,
S. Tepikian,
A. Zaltsman,
A. Zelenski,
K. Zeno,
S.Y. Zhang
[show abstract]
[hide abstract]
ABSTRACT: The relativistic heavy ion collider (RHIC) as the first high energy polarized proton collider was designed to provide polarized proton collisions at a maximum beam energy of 250 GeV. It has been providing collisions at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during the acceleration from injection to 100 GeV with careful control of the betatron tunes and the vertical orbit distortions. However, the intrinsic spin resonances beyond 100 GeV are about a factor of two stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were accelerated to the record energy of 250 GeV in RHIC with a polarization of 46% measured at top energy in 2006. The polarization measurement as a function of beam energy also shows some polarization loss around 136 GeV, the first strong intrinsic resonance above 100 GeV. This paper presents the results and discusses the sensitivity of the polarization survival to orbit distortions.
Particle Accelerator Conference, 2007. PAC. IEEE; 07/2007
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K A Brown,
L Ahrens,
I H Chiang, C Gardner,
D Gassner,
L Hammons,
M Harvey,
J Morris,
A Rusek,
P Sampson,
M Sivertz,
N Tsoupas,
K Zeno
07/2006;
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M Bai,
T Roser,
L Ahrens,
I G Alekseev,
J Alessi,
J Beebe-Wang,
M Blaskiewicz,
A Bravar,
J M Brennan,
D Bruno, [......],
T Satogata,
E Stephenson,
D Svirida,
S Tepikian,
D Trbojevic,
N Tsoupas,
T Wise,
A Zelenski,
K Zeno,
S Y Zhang
[show abstract]
[hide abstract]
ABSTRACT: The Brookhaven Relativistic Heavy Ion Collider (RHIC) has been providing collisions of polarized protons at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the intrinsic spin resonances beyond 100 GeV are about a factor of 2 stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were first accelerated to the record energy of 205 GeV in RHIC with a significant polarization measured at top energy in 2005. This Letter presents the results and discusses the sensitivity of the polarization survival to orbit distortions.
Physical Review Letters 06/2006; 96(17):174801. · 7.37 Impact Factor
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F. Pilat,
L. Ahrens,
M. Bai,
D.S. Barton,
J. Beebe-Wang,
M. Blaskiewicz,
J.M. Brennan,
D. Bruno,
P. Cameron,
R. Connolly, [......],
S. Tepikian,
R. Tomas,
D. Trbojevic,
N. Tsoupas,
J. Tuozzolo,
K. Vetter,
A. Zaltsman,
K. Zeno,
S.Y. Zhang,
W. Zhang
[show abstract]
[hide abstract]
ABSTRACT: The 5<sup>th</sup>year of RHIC operations, started in November 2004 and expected to last till June 2005, consists of a physics run with Cu-Cu collisions at 100 GeV/u followed by one with polarized protons (pp) at 100 GeV [1]. We will address here the overall performance of the RHIC complex used for the first time as a Cu-Cu collider, and compare it with previous operational experience with Au, PP and asymmetric d-Au collisions. We will also discuss operational improvements, such as a squeeze to 85cm in the high luminosity interaction regions from the design value of 1m, system improvements, machine performance and limitations, and address reliability and uptime issues.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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H. Huang,
L.A. Ahrens,
M. Bai,
K. Brown,
E.D. Courant, C. Gardner,
J.W. Glenn,
R.C. Gupta,
A.U. Luccio,
W.W. MacKay,
V. Ptitsyn,
T. Roser,
S. Tepikian,
N. Tsoupas,
E. Willen,
A. Zelenski,
K. Zeno,
M. Okamura,
J. Takano,
F. Lin
[show abstract]
[hide abstract]
ABSTRACT: The RHIC spin program requires 2×10<sup>11</sup>proton/bunch with 70% polarization. As the injector to RHIC, AGS is the bottleneck for preserving polarization: there is no space for a full snake to overcome numerous depolarizing resonances. An ac dipole and a partial snake have been used to preserve beam polarization in the past few years. Two helical snakes have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate all depolarizing resonances encountered during acceleration. This paper presents the setup and preliminary results.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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T. Satogata,
L. Ahrens,
M. Bai,
J. Beebe-Wang,
M. Blaskiewicz,
J.M. Brennan,
K.A. Brown,
D. Bruno,
P. Cameron,
J. Cardona, [......],
C. Montag,
F. Pilat,
V. Ptitsyn,
T. Roser,
K. Smith,
S. Tepikian,
D. Trbojevic,
N. Tsoupas,
S.Y. Zhang,
J. van Zeijts
[show abstract]
[hide abstract]
ABSTRACT: Deuteron and gold beams have been accelerated to a collision energy of √s = 200 GeV/u in the Relativistic Heavy Ion Collider (RHIC), providing the first asymmetric-species collisions of this complex. Necessary changes for this mode of operation include new ramping software and asymmetric crossing angle geometries. This paper reviews machine performance, problems encountered and their solutions, and accomplishments during the 16 weeks of ramp-up and operations.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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H. Huang,
L. Ahrens,
J.G. Alessi,
I. Alekseev,
M. Bai,
J. Beebe-Wang,
S. Brarvar,
M. Brennan,
K.A. Brown,
G. Bunce, [......],
D. Svirida,
S. Tepikian,
D. Trbojevic,
N. Tsoupas,
D. Underwood,
J. van Zeijts,
J. Wood,
A. Zelenski,
K. Zeno,
S.Y. Zhang
[show abstract]
[hide abstract]
ABSTRACT: Polarized proton beam has been accelerated and stored at 100GeV in Relativistic Heavy Ion Collider (RHIC) to study spin effects in the hadronic reactions. The essential equipment includes four Siberian snakes and eight spin rotators in two RHIC rings, a partial snake in the AGS, fast relative polarimeters, and ac dipoles in the AGS and RHIC. This paper summarizes the performance of RHIC as a polarized proton collider and of AGS as the injector to RHIC.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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K.A. Brown,
L. Ahrens,
S. Bellavia,
S. Binello,
B. Brelsford,
D. DuMont,
W. Eng, C. Gardner,
D. Gassner,
J.W. Glenn, [......],
S. Nemesure,
D. Phillips,
A. Rusek,
J. Ryan,
T. Shrey,
L. Snydstrup,
N. Tsoupas,
B. VanKuik,
S. Zahariou-Cohen,
K. Zeno
[show abstract]
[hide abstract]
ABSTRACT: Brookhaven's AGS Booster has been modified to deliver slow extracted beam to a new beam line, the NASA Space Radiation Laboratory (NSRL). This facility was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The design of the resonant extraction system has been described. A more detailed description, which includes predictions of the slow extracted beam time structure has been described. In this report we present results of the system commissioning and performance.
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the; 06/2003
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J. Wei,
J. Beebe-Wang,
M. Blaskiewicz,
J. Brodowski,
A. Fedotov, C. Gardner,
Y.Y. Lee,
D. Raparia,
V. Danilov,
J. Holmes,
C. Prior,
G. Rees,
S. Machida
[show abstract]
[hide abstract]
ABSTRACT: Injection is key in the low-loss design of high-intensity proton
facilities like the Spallation Neutron Source (SNS). During the design
of both the accumulator and the rapid-cycling-synchrotron version of the
SNS, extensive comparison has been made to select injection scenarios
that satisfy SNS's low-loss design criteria. This paper presents issues
and considerations pertaining to the final choice of the SNS injection
systems
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001; 02/2001
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[show abstract]
[hide abstract]
ABSTRACT: Linear coupling, introduced by skew quadrupoles, has been used for
several years to enhance the multi-turn injection efficiency of Au and
other heavy ions in the AGS Booster. In this paper we describe our
latest measurements of the injection process and compare with models
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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L.A. Ahrens,
J. Alessi,
M. Blaskiewicz,
J.M. Brennan,
K. Brown, C. Gardner,
J.W. Glenn,
T. Roser,
K.S. Smith,
W. VanAsselt,
S.Y. Zhang
[show abstract]
[hide abstract]
ABSTRACT: The Brookhaven AGS provides 24 GeV protons for a multi-user
program of fixed-target high energy physics experiments, such as the
study of extremely rare kaon decays. Up to 7×10<sup>13</sup>
protons are slowly extracted over 2.2 seconds each 5.1 seconds. The muon
storage ring of the g-2 experiment is supplied with bunches of
7×10<sup>12</sup> protons. Since the completion of the a 1.9 GeV
Booster synchrotron and installation of a new high-power RF system and
transition jump system in the AGS various modes of operation have been
explored to overcome space charge limits and beam instabilities at these
extreme beam intensities. Experiments have been done using barrier
cavities to enable accumulation of de-bunched beam in the AGS as a
potential path to significantly higher intensities. We report on the
present understanding of intensity limitations and prospects for
overcoming them
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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[show abstract]
[hide abstract]
ABSTRACT: In this paper we describe the latest version of a program we have
used for several years to acquire and analyze turn-by-turn data from
pick-up electrodes in the AGS Booster during injection. The program
determines several parameters of the injected beam including the tunes
and the position and angle of the incoming beam. Examples are given for
bath proton and gold injection
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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W.T. Weng,
J. Alessi,
J. Beebe-Wang,
M. Blaskiewicz,
L. Blumberg,
M. Brennan, C. Gardner,
Y.Y. Lee,
A.U. Luccio,
H. Ludewig,
D. Maletic,
D. Raparia,
A. Ruggerio,
S.Y. Zhang
[show abstract]
[hide abstract]
ABSTRACT: The goal of the proposed National Spallation Neutron Source (NSNS)
is to provide a short pulse proton beam of about 0.5 μs with average
beam power of 1 MW. To achieve such purpose, a proton storage ring
operated at 60 Hz with 1×10<sup>14</sup> protons per pulse at 1
GeV is required. The Accumulator Ring (AR) receives 1 msec long H<sup>-
</sup> beam bunches of 28 mA from a 1 GeV linac. Scope and design
performance goals of the AR are presented, other possible technological
choices and design options considered, but not adopted, are also briefly
reviewed
Particle Accelerator Conference, 1997. Proceedings of the 1997; 06/1997
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L. Ahrens,
J. Alessi,
M. Blaskiewicz,
E. Bleser,
J.M. Brennan,
K. Brown, C. Gardner,
J.W. Glenn,
H. Huang,
K. Reece,
T. Roser,
W. van Asselt,
K. Zeno,
S.Y. Zhang
[show abstract]
[hide abstract]
ABSTRACT: The AGS accelerator complex is into its third year of 60+×10
<sup>12</sup> (teraproton=Tp) per cycle operation. The hardware making
up the complex as configured in 1997 is briefly mentioned. The present
level of accelerator performance is discussed. This includes beam
transfer efficiencies at each step in the acceleration process, i.e.
losses; which are a serious issue at this intensity level. Progress made
in understanding beam behavior at the Linac-to-Booster (LtB) injection,
at the Booster-to-AGS (BtA) transfer as well as across the 450 ms AGS
accumulation porch is presented. The state of transition crossing, with
the gamma-tr jump is described. Coherent effects including those driven
by space charge are important at all of these steps
Particle Accelerator Conference, 1997. Proceedings of the 1997; 06/1997
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[show abstract]
[hide abstract]
ABSTRACT: With the completion of the AGS rf upgrade, and the implementation of a transition {open_quotes}jump{close_quotes}, all of accelerator systems were in place in 1994 to allow acceleration of the proton intensity available from the AGS Booster injector to AGS extraction energy and delivery to the high energy users. Beam commissioning results with these new systems are presented. Progress in identifying and overcoming other obstacles to higher intensity are given. These include a careful exploration of the stopband strengths present on the AGS injection magnetic porch, and implementation of the AGS single bunch transverse dampers throughout the acceleration cycle.
07/1994
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[show abstract]
[hide abstract]
ABSTRACT: Observations of high intensity effects on the proton performance
of the AGS Booster are presented, including present operational limits
and correction methods. The transverse emittances, optimum tune working
points, damping of coherent transverse oscillations and correction of
stopband resonances through third-order are discussed in addition to the
observed tune spread due to space charge forces. The initial
longitudinal phase space distribution, capture and acceleration
parameters and measurements are also given. Operational tools and
strategies relevant to the high intensity setup are mentioned
Particle Accelerator Conference, 1993., Proceedings of the 1993; 06/1993
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[show abstract]
[hide abstract]
ABSTRACT: At the design intensity of 1.5×10<sup>13</sup> ppp, the
space charge tune shift in the AGS Booster at injection has been
estimated to be about 0.35. Therefore, the beam is spread over many
lower order resonance lines and the stopbands have to be corrected to
minimize the amplitude growth by proper compensation of the driving
harmonics resulting from random errors. The observation and correction
of second and third order resonance stopbands in the AGS Booster, and
the establishment of a favorable operating point at high intensity are
discussed
Particle Accelerator Conference, 1993., Proceedings of the 1993; 06/1993
