Alex Bogacz

Sub‐picosecond X‐rays from CEBAF at Jefferson Lab.

A high brightness sub‐picosecond x‐ray source can be created by installing an undulator at Jefferson Lab’s CEBAF, a nuclear physics electron accelerator. Although the beam current is only 100 microamps, the electron beam has an extremely small emittance and energy spread, with the result that one can produce x‐ray beams tunable over the range 5–30keV with an average brightness quite comparable to beamlines at the Advanced Photon Source (APS) at Argonne National Lab. In addition, with rms bunch lengths measured down to 85 fsecs, peak brightness values are much higher than at the APS. Furthermore, this x‐ray source has similar emittance in both horizontal and vertical directions, (a so‐called round beam) making it of very high potential for many applications. In order to determine if indeed such a source is worth pursuing we present “tuning curve” calculations of peak and average flux and brightness for an undulator on CEBAF. They are compared with similar calculations for a dipole and for undulator‐A at th...

Simulations of MANX, A Practical Six Dimensional Muon Beam Cooling Experiment

A helical cooling channel (HCC) has been proposed to quickly reduce the six‐dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. Simulation studies of the HCC have already verified the use of a channel with solenoidal, and helical magnetic fields of constant amplitude where, by moving to a rotating frame, a z or time‐independent Hamiltonian can be obtained for detailed analytic treatment. In the discussion below, the HCC concept has been extended to have momentum‐dependent magnetic field strengths for a six‐dimensional M_uon collider A_nd N_eutrino factory muon beam cooling demonstration eX_periment (MANX). The simulation studies reported here for this experiment have shown that liquid helium can be used as an energy absorber and coolant for superconducting magnetic coils and that the HCC parameters can be varied to reduce the maximum required field magnitudes. These developments make the experiment more practical in that safety requirements are relaxed a...

Electron Spin Rotation And Matching Scheme For ELIC, A High-Luminosity Ring-Ring Electron-Ion Collider

A unique design feature of a polarized Electron‐Ion Collider (ELIC) based on CEBAF is its Figure‐8 shaped storage rings for both electrons and ions, which significantly simplifies beam polarization maintenance and manipulation. The CEBAF accelerator is used as a full energy injector of polarized electron beams into the electron storage ring. While electron polarization is maintained vertical in arcs of the ring, a stable longitudinal spin at four collision points is achieved through vertical crossing bending magnets, solenoid spin rotators, and horizontal orbit bends. Spin matching technique needs to be implemented in order to enhance quantum self‐polarization and minimize depolarization effects. In this paper, we also discuss several important issues related to the use of positron beams, radiative polarization and quantum depolarization effects, as well as spin in ELIC.

Beam Physics for the 12 GeV Cebaf Upgrade Project

Beam physics aspects of the 12 GeV Upgrade of CEBAF are presented. The CEBAF Upgrade to 12 GeV is achieved via 5.5 recirculations through the linacs, and the installation of 10 new high-gradient cryomodules. A new experimental hall, Hall D, is envisioned at the end of the North Linac. Simulation results for a straight-ahead and a recirculated injector are summarized and compared. Beam transport designs are discussed and evaluated with respect to matching and beam breakup (BBU) optimization. Effects of synchrotron radiation excitation on the beam properties are calculated. BBU simulations and derived specifications for the damping of higher order modes of the new 7-cell cavities are presented. The energies that provide longitudinal polarization in multiple experimental halls simultaneously are calculated. Finally, detailed optics of the Hall D transport line has been obtained.

ER@CEBAF, a 7 GeV, 5-Pass, Energy Recovery Experiment

A multiple-pass, high-energy ERL experiment at the JLab CEBAF will be instrumental in providing necessary information and technology testing for a number of possible future applications and facilities such as Linac-Ring based colliders, which have been designed at BNL (eRHIC) and CERN (LHeC), and also drivers for high-energy FELs and 4th GLS. ER@CEBAF is aimed at investigating 6D optics and beam dynamics issues in ERLs, such as synchrotron radiation effects, emittance preservation, stability, beam losses, multiple-pass orbit control/correction, multiple-pass beam dynamics in the presence of cavity HOMs, BBU and other halo studies, handling of large (SR induced) momentum spread bunches, and development of multiple-beam diagnostics instrumentation. Figure 1: 12 GeV CEBAF recirculating linac. Location of chicane and dump line for ER@CEBAF. Since it was launched 2+ years ago, the project has progressed in defining the necessary modifications to CEBAF (Fig. 1, Tab. 1, 2), including a 4-dipole phase chicane in recirculation Arc A, beam extraction and a dump line at the end of the south linac, and additional dedicated multiplebeam diagnostics. This equipment can remain in place to Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy, † and by Jefferson Science Associates, LLC under Contract No. DEAC05-06OR23177 with the U.S. Department of Energy. ‡ Spokesperson. fmeot@bnl.gov; satogata@jlab.org Table 1: Machine/Lattice Parameters of ER@CEBAF fRF 1497 MHz RF frequency Elinac 700 MeV Gain per linac (baseline) Einj 79 MeV = Elinac × 123/1090 φFODO 60 deg Per cell, at first NL pass and last SL pass M56 <90 cm Compression, Arc A Extraction 8 deg Angle to dump line

Progress on the Large Hadron electron Collider

In this work we examine the motivation and design of the Large Hadron electron Collider (LHeC). This proposed addition to the LHC will collide 60 GeV electrons with 7 TeV protons to study deep inelastic physics. We discuss the overall physics motivations for the accelerator, the proposed layout, current design considerations, and some beam-dynamics studies. The current design calls for an energy recovery linac to provide the electron beam. Preliminary designs for the optics and interaction region have been included, as well as analyses of the dynamics of both the electron and proton beams.

Design studies of high-luminoisty ring-ring electron-ion collider at CEBAF

Experimental studies of fundamental structure of nucleons require an electron-ion collider of a center-of- mass energy up to 90 GeV at luminosity up to 1035 cm-2 s-1 with both beams polarized. A CEBAF-based collider of 9 GeV electrons/positrons and 225 GeV ions is envisioned to meet this science need and as a next step for CEBAF after the planned 12 GeV energy upgrade of the fixed target program. A ring-ring scheme of this collider developed recently takes advantage of the existing polarized electron CW beam from the CEBAF and a green-field design of an ion complex with electron cooling. We present a conceptual design and report design studies of this high-luminosity collider.