COOL2013 - List of Authors (Stockhorst, H.)

Paper

Title

Page

Stochastic Cooling of a Polarized Proton Beam at COSY

44

H. Stockhorst, R. Gebel, V. Kamerdzhiev, A. Lehrach, B. Lorentz, R. Maier, D. Prasuhn, R. Stassen
FZJ, Jülich, Germany
T. Katayama
GSI, Darmstadt, Germany

Stochastic cooling can increase the spin coherence time in storage ring experiments dedicated to the search of electric dipole moments of protons or deuterons. Since radial magnetic fields may lead to depolarizing spin resonances a first test with a vertical polarized beam at COSY subject to vertical stochastic cooling has been investigated. The polarization was measured at the beginning and the end of flat top momentum with the result that no polarization loss could be observed within five minutes. The spin motion under the influence of stochastic cooling was also studied with the Thomas-BMT equation including the estimated electromagnetic fields for a quarter wave length kicker structure. It is found that the resonance strength in the cooling bandwidth of 1-2 GHz is much smaller than the typical imperfection or intrinsic resonance strengths. The resonance condition of the spin rotation is not fulfilled as the harmonics of cooling RF kicker fields are not in phase with the spin rotation angle per turn. In conclusion it is expected that stochastic cooling will not lead to depolarization even when stochastic cooling is applied for a longer time as in the present experiment.

Slides TUAM1HA02 [2.324 MB]

THAM2HA01

Beam Accumulation and Bunching with Cooling

170

T. Katayama, M. Steck
GSI, Darmstadt, Germany
T. Kikuchi
Nagaoka University of Technology, Nagaoka, Niigata, Japan
I.N. Meshkov
JINR, Dubna, Moscow Region, Russia
H. Stockhorst
FZJ, Jülich, Germany

The accumulation of anti-proton beam in the storage ring was performed at CERN and FNAL with use of a stochastic stacking system. In the original version of the FAIR such a concept was envisaged at the accumulator ring named RESR. However in the modularized start version of FAIR, the RESR was postponed and the new concept of anti-proton accumulation in the High Energy Storage Ring (HESR) was strongly demanded. The barrier bucket system with stochastic cooling was found with simulation work to have enough capabilities to accumulate the pre-cooled 3 GeV anti-proton beam in the HESR. The Proof Of Principle (POP) experiment was performed at the GSI storage ring ESR with the use of Ar and Xe ion beam employing both stochastic and electron cooling. The experimental results were well in agreement with the prediction of the simulation study. The concept of BB accumulation could be applied to the planned Collider of the NICA project at JINR. In the present paper the concept of BB accumulation and the short bunch formation including the space charge effects are presented as well as the analysis of POP experiment.

Slides THAM2HA01 [8.446 MB]

Paper	Title	Page
TUAM1HA02	Stochastic Cooling of a Polarized Proton Beam at COSY	44
	H. Stockhorst, R. Gebel, V. Kamerdzhiev, A. Lehrach, B. Lorentz, R. Maier, D. Prasuhn, R. Stassen FZJ, Jülich, Germany T. Katayama GSI, Darmstadt, Germany
	Stochastic cooling can increase the spin coherence time in storage ring experiments dedicated to the search of electric dipole moments of protons or deuterons. Since radial magnetic fields may lead to depolarizing spin resonances a first test with a vertical polarized beam at COSY subject to vertical stochastic cooling has been investigated. The polarization was measured at the beginning and the end of flat top momentum with the result that no polarization loss could be observed within five minutes. The spin motion under the influence of stochastic cooling was also studied with the Thomas-BMT equation including the estimated electromagnetic fields for a quarter wave length kicker structure. It is found that the resonance strength in the cooling bandwidth of 1-2 GHz is much smaller than the typical imperfection or intrinsic resonance strengths. The resonance condition of the spin rotation is not fulfilled as the harmonics of cooling RF kicker fields are not in phase with the spin rotation angle per turn. In conclusion it is expected that stochastic cooling will not lead to depolarization even when stochastic cooling is applied for a longer time as in the present experiment.
	Slides TUAM1HA02 [2.324 MB]

THAM2HA01	Beam Accumulation and Bunching with Cooling	170
	T. Katayama, M. Steck GSI, Darmstadt, Germany T. Kikuchi Nagaoka University of Technology, Nagaoka, Niigata, Japan I.N. Meshkov JINR, Dubna, Moscow Region, Russia H. Stockhorst FZJ, Jülich, Germany
	The accumulation of anti-proton beam in the storage ring was performed at CERN and FNAL with use of a stochastic stacking system. In the original version of the FAIR such a concept was envisaged at the accumulator ring named RESR. However in the modularized start version of FAIR, the RESR was postponed and the new concept of anti-proton accumulation in the High Energy Storage Ring (HESR) was strongly demanded. The barrier bucket system with stochastic cooling was found with simulation work to have enough capabilities to accumulate the pre-cooled 3 GeV anti-proton beam in the HESR. The Proof Of Principle (POP) experiment was performed at the GSI storage ring ESR with the use of Ar and Xe ion beam employing both stochastic and electron cooling. The experimental results were well in agreement with the prediction of the simulation study. The concept of BB accumulation could be applied to the planned Collider of the NICA project at JINR. In the present paper the concept of BB accumulation and the short bunch formation including the space charge effects are presented as well as the analysis of POP experiment.
	Slides THAM2HA01 [8.446 MB]