The polarized proton and antiproton beam project at U-70 accelerator
V. V. Abramov, I. L. Azhgirey, V. I. Garkusha, V. P. Kartashev, V. V. Mochalov, S. B. Nurushev, V. L. Rykov, P. A. Semenov, A. N. Vasiliev, V. N. Zapolsky, V. G. Zarucheisky
The design and parameters of the polarized-beam facility at U-70 proton synchrotron of NRC Kurchatov Institute - IHEP are presented. The new beamline 24A will provide the polarized proton and antiproton beams for carrying out the rich physics program of the SPASCHARM experiment for comprehensive studies of spin phenomena in a wide spectrum of hadronic reactions in the energy range of 10-45 GeV.
We give an overview of our current/future analytical and numerical work on the spin polarization in high-energy electron storage rings. Our goal is to study the possibility of polarization for the CEPC and FCC-ee. Our work is based on the so-called Bloch equation for the polarization density introduced by Derbenev and Kondratenko in 1975. We also give an outline of the standard approach, the latter being based on the Derbenev-Kondratenko formulas.
The Polarized Electrons for Polarized Positrons (PEPPo) experiment has demonstrated the efficient transfer of polarization from electrons to positrons produced by the bremsstrahlung radiation of a polarized electron beam in a high-$Z$ target. Positron polarization up to 82\% has been measured for an initial electron beam momentum of 8.19 MeV/$c$, limited only by the electron beam polarization. Combined with the high intensity and high polarization performances of polarized electron sources, this technique extends efficient polarized positron capabilities from GeV to MeV electron accelerators. …
The generation of polarized particle beams still relies on conventional particle accelerators, which are typically very large in scale and budget. Concepts based on laser-driven wake-field acceleration have strongly been promoted during the last decades. Despite many advances in the understanding of fundamental physical phenomena, one largely unexplored issue is how the particle spins are influenced by the huge magnetic fields of plasma and, thus, how highly polarized beams can be produced. The realization of laser-plasma based accelerators for polarized beams is now being pursued as a joint e…
Simon van der Meer and his legacy to CERN and particle accelerators
Simon van der Meer是一位杰出的科学家，也是加速器领域真正的巨人。他对加速器科学的开创性贡献是必不可少的，直到今天，在我们寻求满足现代粒子物理学的要求。无论我们谈论的是欧洲核子研究中心和费米实验室的长基线中微子物理学或反质子-质子物理学，还是大型强子对撞机的质子-质子物理学，他的技术和发明都是现代成功的重要组成部分。Simon van der Meer和Carlo Rubbia是1984年第一批获得诺贝尔物理学奖的CERN科学家。他不太为人所知的贡献涵盖了加速器科学的一系列主题，从磁铁设计到电源设计，束流测量，慢束流提取，复杂的程序和控制。
We report the initial considerations of using linearly polarized optical transition radiation (OTR) to characterize the electron beams of laser plasma accelerators (LPAs) such as at the Univ. of Texas at Austin. The two LPAs operate at 100 MeV and 2-GeV, and they currently have estimated normalized emittances at ~ 1-mm mrad regime with beam divergences less than 1/γ and beam sizes to be determined at the micron level. Analytical modeling results indicate the feasibility of using these OTR techniques for the LPA applications.
The acceleration of polarized electrons, positrons, protons and ions in strong laser and plasma fields is a very attractive option to obtain polarized beams in the multi-MeV range. Recently, there has been substantial progress in the understanding of the dominant mechanisms leading to high degrees of polarization, in the numerical modelling of these processes and in their experimental implementation. This review article presents an overview on the current status of the field, on the concepts of polarized laser-plasma accelerators and of the beam polarimetry.
In situ generation of a high-energy, high-current, spin-polarized electron beam is an outstanding scientific challenge to the development of plasma-based accelerators for high-energy colliders. In this Letter we show how such a spin-polarized relativistic beam can be produced by ionization injection of electrons of certain atoms with a circularly polarized laser field into a beam-driven plasma wakefield accelerator, providing a much desired one-step solution to this challenge. Using time-dependent Schrödinger equation (TDSE) simulations, we show the propensity rule of spin-dependent ionization…
国际直线对撞机（英语：International Linear Collider，ILC）是一个200-500 GeV的高亮度线性电子-正电子对撞机，基于1.3 GHz超导射频（SCRF）加速腔。ILC的总覆盖面积约为31 km，设计的峰值亮度为2 x 10^34 cm^-2 s^-1。该综合体包括一个极化电子源，一个基于波荡器的正电子源，两个6.7公里周长的阻尼环，两级聚束压缩器，两个11公里长的主直线加速器和一个4.5公里长的束流传输系统。本报告是四卷参考设计报告的第三卷（加速器），描述了ILC的设计和成本。
The Main Injector (MI) at Fermilab currently produces high-intensity beams of protons at energies of 120 GeV for a variety of physics experiments. Acceleration of polarized protons in the MI would provide opportunities for a rich spin physics program at Fermilab. To achieve polarized proton beams in the Fermilab accelerator complex, detailed spin tracking simulations with realistic parameters based on the existing facility are required. This report presents studies at the MI using a single 4-twist Siberian snake to determine the depolarizing spin resonances for the relevant synchrotrons. Resul…
Brilliant multi-GeV Compton gamma-ray source seeded by a photon accelerator
University of Gothenburg（哥德堡大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；University of York（约克大学）；Chalmers University of Technology（查尔姆斯理工大学）；University of Michigan（密歇根大学）
High-gradient and high-efficiency acceleration in plasma-based accelerators has been demonstrated, showing its potential as the building block for a future collider operating at the energy frontier of particle physics. However, generating and accelerating the required spin-polarized beams in such a collider using plasma-based accelerators has been a long-standing challenge. Here we show that the passage of a highly relativistic, high-current electron beam through a single-species (ytterbium) vapor excites a nonlinear plasma wake by primarily ionizing the two outer 6s electrons. Further photoio…
Fermilab is dedicated to hosting world-class experiments in search of new physics that will operate in the coming years. The Muon g-2 Experiment is one such experiment that will determine with unprecedented precision the muon anomalous magnetic moment, which offers an important test of the Standard Model. We describe in this study the accelerator facility that will deliver a muon beam to this experiment. We first present the lattice design that allows for efficient capture, transport, and delivery of polarized muon beams. We then numerically examine its performance by simulating pion productio…
This paper summarizes the state of the art of photocathode based on III-V semiconductors for spin polarized electron beam production. The limitations preventing this class of material to provide the long term reliability at the highest average beam currents necessary for some of the new accelerator facilities or proposed upgrades of existing ones are illustrated. Promising alternative classes of materials are identified showing properties that can be leveraged to synthesize photocathode structures that can outperform III-V semiconductors in the production of spin polarized electron beams and s…
Angular momentum dynamics of vortex particles in accelerators
School of Physics and Engineering, ITMO University（ITMO大学物理与工程学院）；Petersburg Nuclear Physics Institute of NRC “Kurchatov Institute”（核科学研究所“库尔恰托夫研究所”圣彼得堡核物理研究所）
A method of generating spin polarized proton beams from a gas jet by using a multi-petawatt laser is put forward. With currently available techniques of producing pre-polarized monatomic gases from photodissociated hydrogen halide molecules and petawatt lasers, proton beams with energy ~ 50 MeV and ~ 80 % polarization are proved to be obtained. Two-stage acceleration and spin dynamics of protons are investigated theoretically and by means of fully self-consistent three dimensional particle-in-cell simulations. Our results predict the dependence of the beam polarization on the intensity of the …
In recent years, Laser Plasma Acceleration (LPA) has become a promising alternative to conventional RF accelerators. However, so far, it has only been theoretically shown that generating polarized LPA beams is possible. The LEAP (Laser Electron Acceleration with Polarization) project at DESY aims to demonstrate this experimentally for the first time, using a pre-polarized plasma target. The electron polarization will be measured with photon transmission polarimetry, which makes use of the production of circularly polarized bremsstrahlung during the passage of the electron beams through a suita…
We report on the concept of an innovative source to produce polarized proton/deuteron beams of a kinetic energy up to several GeV from a laser-driven plasma accelerator. Spin effects have been implemented into the PIC simulation code VLPL to make theoretical predictions about the behavior of proton spins in laser-induced plasmas. Simulations of spin-polarized targets show that the polarization is conserved during the acceleration process. For the experimental realization, a polarized HCl gas-jet target is under construction using the fundamental wavelength of a Nd:YAG laser system to align the…
The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-$Z$ target. Positron polarization up to 82\% have been measured for an initial electron beam momentum of 8.19~MeV/$c$, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access …
