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Ptitsyn, V.

Publications and source records attributed to Ptitsyn, V..

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Polarization preservation of polarized deuteron beams in the electron ion collider at Brookhaven National Laboratory

The physics program at the future electron ion collider (EIC) calls for polarized neutron beams at high energies. The best neutron carriers are 3 He nuclei and deuterons. Both neutron carriers are expected to be utilized by the spin physics program in the EIC. Owing to the small magnetic moment anomaly of a deuteron particle, significantly higher magnetic fields are required for spin rotation, so that full Siberian snakes are not feasible. However, the resonance strengths are weak, and the number of resonances is small. It is possible to deal with individual resonances using conventional methods such as a betatron tune jump and vertical ac dipole for intrinsic depolarizing resonances, and a weak partial snake for imperfection resonances. This study employed a realistic magnet ramp rate and parameters (both transverse and longitudinal emittances, as well as realistic lattices) to show that it is possible to accelerate polarized deuterons beyond 100 GeV/n. This paper summarizes the details of the feasibility of a polarized deuteron beam for the future EIC at Brookhaven National Laboratory.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Simulation of Transparent Spin Experiment in RHIC

The transparent spin mode has been proposed as a new technique for preservation and control of the spin polarization of an ion beam in a synchrotron. The ion rings of the proposed Jefferson Lab Electron-Ion Collider adopted this technique in their figure-8 design. The transparent spin mode can also be setup in a racetrack with two identical Siberian snakes. There is a proposal to test the predicted features of the spin transparent mode in RHIC, which already has all of the necessary hardware capabilities. We have earlier analytically estimated the setup parameters and developed a preliminary experimental plan. In this paper we describe simulations of the proposed experiment using a Zgoubi model of RHIC. We present simulation of the polarization preservation during acceleration in the transparent spin mode. We also demonstrate polarization control by simulating an adiabatic polarization adjustment. A procedure to measure the strength of the spin transparent resonance is illustrated.

Morozov, Vasiliy↗
DOE OSTI2019

EXPERIMENTAL VERIFICATION OF TRANSPARENT SPIN MODE IN RHIC

High electron and ion polarizations are some of the key design requirements of a future Electron Ion Collider (EIC). The transparent spin mode, a concept inspired by the figure 8 ring design of JLEIC, is a novel technique for preservation and control of electron and ion spin polarizations in a collider or storage ring. It makes the ring lattice "invisible" to the spin and allows for polarization control by small quasi-static magnetic fields with practically no effect on the beam’s orbital characteristics. It offers unique opportunities for polarization maintenance and control in Jefferson Lab’s JLEIC and in BNL’s eRHIC. The transparent spin mode has been demonstrated in simulations and we now plan to test it experimentally. We present a design of an experiment using a polarized proton beam stored in one of the RHIC rings. In the experiment, one of the RHIC rings is configured in the transparent spin mode by aligning the axes of its two Siberian snakes. The experiment goals, procedures, hardware requirements and expected results are presented.

Morozov, V.S.↗
DOE OSTI2019

Spin response function for spin transparency mode of RHIC

In the Spin Transparency (ST) mode of RHIC, the axes of its Siberian snakes are parallel. The spin tune in the ST mode is zero and the spin motion becomes degenerate: any spin direction repeats every particle turn. In contrast, the lattice of a conventional collider determines a unique stable periodic spin direction, so that the collider operates in the Preferred Spin (PS) mode. Contributions of perturbing magnetic fields to the spin resonance strengths in the PS mode are usually calculated using the spin response function. However, in that form, it is not applicable in the ST mode. This paper presents a response function formalism expanded for the ST mode of operation of conventional colliders with two identical Siberian snakes in the highly-relativistic limit. We present calculations of the spin response function for RHIC in the ST mode.

Morozov, V. S.↗
DOE OSTI2019

Measurement of the Spin Tune Using the Coherent Spin Motion of Polarized Protons in a Storage Ring

This Letter reports the first spin tune measurement at high energies (24 and 255 GeV) with a driven coherent spin motion. To maintain polarization in a polarized proton collider, it is essential to know the spin tune of the polarized proton beam, which is defined as the number of full spin precessions per revolution. A nine-magnet spin flipper has demonstrated high spin-flip efficiency in the presence of two Siberian snakes. The spin flipper drives a spin resonance with a given frequency (or tune) and strength. When the drive tune is close to the spin tune, the proton spin direction is not vertical anymore, but precesses around the vertical direction. By calculating the precession frequency of the horizontal component, the spin tune can be precisely measured. A driven coherent spin motion and fast turn-by-turn polarization measurement are keys to the measurement. The vertical spin direction is restored after turning the spin flipper off and the polarization value is not affected by the measurement. In conclusion, the fact that this manipulation preserves the polarization makes it possible to measure the spin tune during the operation of a high energy accelerator.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

A state of the art current-septum dipole magnet

Here, the acceleration process of charged particle beams often requires the use of few acceleration stages to provide the beam with the desired energy. The extraction of the beam from one acceleration stage and the injection to the next, both require a special type of magnet which comes under the name septum magnet. Such a magnet generates a strong field in one region and a very low field in another region with the two regions separated by a very thin material (septum). The septum thickness of such a magnet should be as thin as possible to reduce the strength of other devices, like kickers, which are involved in the extraction or injection processes. A thin septum is also advantageous during the slow beam extraction process to reduce the beam losses at the septum. One of the methods which in theory can generate very large differences in field strength in adjacent field regions separated by a thin septum, is the use of two thin parallel current sheets of infinite dimensions. In practice we use other devices that can approximate such an abrupt change of the magnetic field within the septum thickness. In this paper we describe such a device, the DC current septum, we present results from the study of its electromagnetic properties, and we discuss a method to minimize the magnetic field in the region which requires a very small magnetic field. We also provide some results from the experimental measurements of the magnetic field generated by the D6 current septum magnet which is installed in the experimental beam line of the NASA’s Space Radiation Laboratory (NSRL) facility [1],[2] at Brookhaven National Laboratory (BNL). This septum magnet is part of the beam’s extraction system from the AGS-Booster into the NSRL beam line for material and biological studies.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

The CBETA Fractional Arc Test

As part of this development effort, the Cornell-BNL Energy recovery linac Test Accelerator (CBETA) [3], a 4-pass, 150 MeV energy recovery linac (ERL), utilizing a Non-scaling Fixed Field Alternating-gradient (NS-FFA) permanent magnet return loop, is currently under design and construction at Cornell University through the joint collaboration of Brookhaven National Lab (BNL) and the Cornell Laboratory for Accelerator based Sciences and Education (CLASSE). Building on the significant advancements in high-brightness photoelectron sources and SRF technology at Cornell, as well as the FFA magnet and lattice design expertise from BNL, CBETA will establish the operation of a multi-turn SRF based ERL utilizing a compact FFA return loop with large energy acceptance (a factor of roughly 3.6 in energy), and thus demonstrate one possible cost-reduction technology under consideration for the eRHIC design. Moreover, successful completion of the CBETA project requires the study and measurement of many critical phenomena relevant to designing the EIC: the Beam-Breakup (BBU) instability, halo-development and collimation, growth in energy spread from Coherent Synchrotron Radiation (CSR), and CSR micro bunching, and thus should provide valuable insight to the EIC and ERL communities. In order to demonstrate the viability of the CBETA design, the Fractional Arc Test (FAT) was added to the CBETA commissioning sequence.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

CBETA Technical Report (CBETA Note #31)

This document includes twelve sections related to the previous Fractional Arc Test (FAT), CBETA final installation plan has which follows the milestones signed in the contract with the New York State Energy Development Authority (NYSERDA). In the second part we provide a plan for final installation, hardware and software preparation and the beam commissioning.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

High spin flip efficiency at 255GeV for polarized protons in a ring with two full Siberian Snakes

In polarized proton collision experiments, it is highly advantageous to flip the spin of each bunch of protons during the stores to reduce the systematic errors . Experiments done at energies less than 2GeV have demonstrated a spin flip efficiency over 99%. At high energy colliders with Siberian Snakes, a single magnet spin flipper does not work because of t he large spin tune spread and the generation of multiple, overlapping resonances. A more sophisticated spin flipper, constructed of 9-dipole magnets was used to flip the spin in Relativistic Heavy Ion Collider(RHIC). Special optics choice was also used to make the spin tune spread very small. A 97% spin flip efficiency was measured both at 24GeV and 255GeV. Lastly, these results show that efficient spin flipping can be achieved at high energies using a 9-magnet spin flipper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Design of a modified Halbach magnet for the CBETA Project

A modified Halbach magnet has been designed to be installed in the splitter/merger section of the CBETA project which is under construction at Cornell University. The splitter/merger of the CBETA consists of 4 beam lines and is shown in Fig. 1. Two of the functions of the splitter/merger lines are; first to match the beam parameters at the exit of the Energy Recovery Linac (ERL) to those at the entrance of the Fixed Field Alternating Gradient (FFAG) arc, and second to place the trajectories of the reference particles of the beam bunches at the entrance of the FFAG arc on specified trajectories as they determined by the beam optics of the FFAG arc. In this technical note we present results from the 2D and 3D electromagnetic analysis of the S4.BEN01 magnet which is one of the dipole magnets of the 150 MeV line of the splitter/merger. The present design of the S4.BEN01 magnet, is based on a modified Halbach-type permanent magnet. To justify our suggestion of using a Halbach type of magnet instead of an electromagnet for the S4.BEN01 magnet we devote an APPENDIX A in which we provide details on the design of an electromagnet for the S4.BEN01 magnet and in the section under conclusion will list the pros and cons of the two designs.

43 PARTICLE ACCELERATORS↗