The Proton EDM Experiment (pEDM) is the first direct search for the proton electric dipole moment (EDM) with the aim of being the first experiment to probe the Standard Model (SM) prediction of any particle EDM. Phase-I of pEDM will achieve 10^-29 e·cm, improving current indirect limits by four orders of magnitude. This will establish a new standard of precision in nucleon EDM searches and offer a unique sensitivity to better understand the Strong CP problem. The experiment is ideally positioned to explore physics beyond the Standard Model (BSM), with sensitivity to axionic dark matter via the signal of an oscillating proton EDM and across a wide mass range of BSM models from 𝒪(1GeV) to 𝒪(10^3TeV). Utilizing the frozen-spin technique in a highly symmetric storage ring that leverages existing infrastructure at Brookhaven National Laboratory (BNL), pEDM builds upon the technological foundation and experimental expertise of the highly successful Muon g-2 Experiments. With significant R&D and prototyping already underway, pEDM is preparing a conceptual design report (CDR) to offer a cost-effective, high-impact path to discovering new sources of CP violation and advancing our understanding of fundamental physics. It will play a vital role in complementing the physics goals of the next-generation collider while simultaneously contributing to sustaining particle physics research and training early-career researchers during gaps between major collider operations.

This note presents key findings for the ESR main magnet dipole power supplies (PS), where we find the current ripple specification to be close to or beyond the state-of-the-art. These specifications originate from beam-beam considerations, with the requirement to limit the ripple-induced hadron emittance growth to below 10%/hour. Beam dynamics that drive this PS ripple specification arise from the beam motions at the Interaction Point (IP). The frequency of the motions can be separated into "low", compared to the betatron frequency, and "high", i.e. around the betatron frequency and harmonics. In terms of the driving frequency, "low" implies ƒ<<ƒ0vx,y and "fast" means ƒ≈{ƒ0vx,y, ƒ0(1-vx,y, etc.}, where ƒ0=1/T0=78.2 kHz is the revolution frequency, and vx,y are the fractional parts of the betatron tunes. Frequencies higher than ƒ0/2 will be folded back due to the particles sampling the field once per turn. To provide flexibility for future lattice adjustments and working point variations, we do not consider the tunes as fixed. Instead, we assume a certain margin and allow them to potentially fall within the range of 0.1

Noise driven emittance growth is modified by the presence of coherent forces. Closed form asymp-toic growth rates are given for two frequency distributions. The analytic results are compared with tracking, showing good agreement. Purely numerical results for a parabolic frequncy distribution are also presented. If a small antidamping force is present then additional, real frequency shifts increase growth rates.

The 400 MeV LINAC1 of the proposed eRHIC collider1 is the first acceleration stage of the 18 GeV electron accelerator. The second acceleration stage of the electron accelerator is the Rapid Cycling Synchrotron (RCS), which can increase the energy of the electron bunches to 18 GeV and subsequently extract transfer and inject the 18 GeV electron bunches into the 18 GeV electron Storage Ring (SR) to collide with the hadron bunches of the existing (Relativistic Heavy Ion Collider (RHIC)) accelerator. This paper describes the beam optics of the transfer line between the 400 MeV LINAC and the RCS accelerator (LtRCS). The function of the LtRCS line is twofold, first to transfer the electron beam from the exit of the 400 MeV LINAC to the injection point of the RCS1 and second to rotate the stable spin direction of the polarized electrons from the longitudinal direction to the vertical. A detailed description of the constraints to be satisfied by the LtRCS transfer line will be given. A section will also be devoted to discuss the spin rotator2.

The plasma cascade instability (PCI) is a proposed mechanism for microbunching in electron beams without dipole magnets. Existing theory is limited to wave propagation that is orthogonal to the advective compression direction. This work provides a theory allowing for wave propagation in arbitrary directions.

The low energy RHIC electron cooling (LEReC) project at Brookhaven employs a linac to supply electrons with kinetic energies from 1.6 to 2.6 MeV. Along with cooling the stored ion beam the electron bunches create a coherent space charge field which can cause emittance growth. This process is investigated both analytically and through simulation.

A 56 MHz superconducting RF cavity was designed and installed in the Relativistic Heavy Ion Collider (RHIC). It is the first superconducting quarter wave resonator (QWR) operating in a high-energy storage ring. We discuss herein the cavity operation with Au+Au collisions, and with asymmetrical Au+He3 collisions. The cavity is a storage cavity, meaning that it becomes active only at the energy of experiment, after the acceleration cycle is completed. With the cavity at 300 kV, an improvement in luminosity was detected from direct measurements, and the bunch length has been reduced. The uniqueness of the QWR demands an innovative design of the higher order mode dampers with high-pass filters, and a distinctive fundamental mode damper that enables the cavity to be bypassed during the acceleration stage.

LEReC project uses a DC photoemission gun with multi-alkali (CsK2Sb or NaK2Sb) cathode [1]. To get 24 mm “flat-top” distribution, 32 Gaussian laser bunches with 0.6 mm rms length are stacked together with 0.75 mm distance [2]. In this case one cannot simply use a 1 cm rms length Gaussian/step/delta bunch for short range wake field simulation since a 0.6 mm bunch contains frequency much higher than the 1 cm bunch. A short range wake field simulation was done using CST Particle Studio™ with 0.6 mm rms Gaussian bunch at the speed of light, and this result was compared with the result for 1 cm rms Gaussian bunch in Figure 1, from where one notice that the wake potential for the 0.6 mm bunch is ~10 times higher than that of the 1 cm bunch. The wake potential of the 0.6 mm bunch, as well as the charge distribution, was then “shift and stack” every 0.75 mm, the normalized results are shown in Figure 2. The wake loss factor (WLF) is the integration of the product of wake potential and normalized bunch charge, and the energy spread factor (ESF) is the rms deviation from the average energy loss. It is calculated by summing the weighted squares of the differences and taking the square root of the sum. These two factors were then divided by β2 for 1.6 MV beam energy. The wake loss factor is at 0.86 V/pC and energy spread factor is at 0.54 V/pC rms. With 100 pC electron bunch, the energy spread inter-bunch is 54 V rms.

High Order Mode (HOM) power is produced by high current linear accelerators. In this paper, we report a new method to estimate the HOM power generation and energy spread from multiple bunch patterns in the time domain on multiple HOMs. These methods can be used to evaluate the HOM power and energy spread induced by the HOM field, and to optimize the design of SRF cavities to minimize the HOM power and the energy spread induced by the HOMs.

In this article, I discuss existing and planned techniques for cooling high-energy hadron beams, provide practical formulae for estimating cooling rates, and address difficulties and challenges.

We describe a proposal to search for an intrinsic electric dipole moment (EDM) of the proton with a sensitivity of \targetsens, based on the vertical rotation of the polarization of a stored proton beam. The New Physics reach is of order $10^~3$TeV mass scale. Observation of the proton EDM provides the best probe of CP-violation in the Higgs sector, at a level of sensitivity that may be inaccessible to electron-EDM experiments. The improvement in the sensitivity to $\theta_{QCD}$, a parameter crucial in axion and axion dark matter physics, is about three orders of magnitude.

We show that, for a test ion moving in a collisionless single-species electron plasma, exact analytical solutions can be obtained for certain anisotropic velocity distributions of the electron plasma. By comparing the analytical formula with the numerical results calculated for the more realistic Maxwellian plasma, we demonstrate that plasmas with three different velocity distributions behave similarly for ions moving with velocity smaller than the velocity spread of the electrons. Furthermore, we show that the response of the electron density to a rest ion decays exponentially with distance, provided the anisotropic velocity distribution exhibits elliptical symmetry.

In this paper we present status and plans for the 20- MeV R&D energy recovery linac (ERL), which is under construction at Collider Accelerator Department at BNL. The facility is based on high current (up to 0.5 A of average current) super-conducting 2.5 MeV RF gun,single-mode super-conducting 5-cell RF linac and about 20-m long return loop with very flexible lattice. The R&D ERL, which is planned for commissioning in early 2009, aims to address many outstanding questions relevant for high current, high brightness energy-recovery linacs.

The Los Alamos Proton Storage Ring suffers from a vi- olent, high frequency, transverse instability at high beam current. The Spallation Neutron Source will be similar to the PSR and one must insure that the PSR instability will not keep SNS from reaching its design goal. Efforts toward understanding the instability are described.

Transverse instabilities in synchrotrons with large space charge tune shift are considered. In particular the variation of the incoherent tune with longitudinal position in the bunch is included. Expansion in an appropriate basis set results in an eigenvalue problem which reduces to previously derived expressions when the space charge tune spread is ignored. The regime where the synchrotron tune is negligible compared to the space charge tune shift is also considered. Under appropriate conditions this results in a significantly smaller growth rate than the ones obtained using the weak coupling formalism. Finally, the effect of octupole induced betatron tune spread is included, resulting in a technique for estimating the maximum stable current.

A relativistic model of pulsar polarization is presented which involves radio emission from the open field line region at radii well within the light cylinder. The model incorporates relativistic plasma flow when the corotation component of the plasma velocity is included. The model predicts that the centroid of the position angle curve arrives later than the centroid of the intensity profile by an amount 4r/c, where r is the emission radius. Our assumptions should hold for coherent curvature emission and for plasma maser emission mechanisms that do not employ a cyclotron resonance, as long as propagation effects are not too large. Application to pulsars with well-ordered position angle swings and periods between 0.06 and 3.7 s gives emission radii of not more than 2000 km for 0.43 and 1.4 GHz. In most cases, the upper bound is 100-300 km, and in 11 cases the emission radii are known within error bars of less than 50%. The results agree well with the emission radii predicted using a radius-to-pulse-width mapping. We find that the symmetry breaking effects of the corotation velocity may help explain a general asymmetry found in pulsar intensity profiles and may strongly affect the intensity profiles of short-period pulsars.