William A. Barletta

Characteristics of a high energy μ+μ− collider based on electro‐production of muons

We analyze the design of a high energy μ+μ− collider based on electro‐production of muons. We derive an expression for the luminosity in terms of analytic formulae for the electron‐to‐muon conversion efficiency and the electron beam power on the production target. On the basis of studies of self‐consistent sets of collider parameters under ‘‘realistic’’ (‘‘optimistic’’) assumptions about available technology with beam cooling, we find the luminosity limited to 10−7 cm−2 s−1 (1028 cm−2 s−1). We also identify major technological innovations that will be required before μ+μ− colliders can offer sufficient luminosity (1030 cm−2 s−1) for high energy physics research.

The proposed injection system for an asymmetric B factory in the PEP tunnel

The proposed asymmetric energy B factory to be built in the PEP (Positron-Electron Project) tunnel will require a highly effective and profuse source of low-emittance electron and positron bunches. The specifications and required parameters of the injection system are shown. The B factory will consist of two rings of equal size, a 9 GeV electron ring and a 3.1 GeV positron ring, each with 1658 bunches, and with total circulating currents of 1.5 and 2.1 A, respectively. As the luminosity lifetime of the collider is expected to be about 2 h, the injector should be capable of filling the rings in a small fraction of an hour. With some simple modifications, the SLC linac with its damping rings and positron source is ideally suited to fulfil this function effectively. The injector will consist of the first 19 sectors of the linac the two damping rings, and the positron source. The overall injection system is described.<<ETX>>

Modeling photo-desorption in high current storage rings

The authors present a simple phenomenological model of photo-desorption that includes effects of dose dependence and diffuse photon reflection to compute the leveling of gas loads in beamlines of high current storage rings that typify heavy flavor factories. This model is also used to estimate chamber commissioning times.<<ETX>>

Vacuum design for a Superconducting Mini-Collider

The phi factory (Superconducting Mini-Collider or SMC) proposed for construction at UCLA is a single storage ring with circulating currents of 2 A each of electrons and positrons. The small circumference exacerbates the difficulties of handling the gas load due to photodesorption from the chamber walls. The authors analyze the vacuum system for the phi factory to specify design choices. It is concluded that the SMC vacuum system, while more challenging than that of existing storage rings, is within the bounds of sound engineering practices. The antechamber moves the gas load away from the beam, thereby lowering the required distributed pumping. To minimize photodesorption, stainless steel backed by a Cu cooling bar has been selected for the chamber material. This design allows for chamber commissioning in approximately=300 hours of ring operation.<<ETX>>

RADIATION FROM FINE, INTENSE, SELF-FOCUSSED BEAMS AT HIGH ENERGY

A theoretical analysis is presented of the radiation emitted when an intense, relativistic, low emittance electron beam propagates through a channel of preionized gas. The beam will self-focus to a small radius and radiate, in the self-induced magnetic field, and it will emit an intense burst of gamma rays. If the beam is subject to a conventional wiggler field, the result will be a “wiggled channel,” and a subsequent pulse of high energy electrons will radiate, more effectively than in the absence of ions, a substantial fraction (≈ 0.1%) of its power coherently as an X-ray laser beam.

A RF–linac, FEL based drive beam injector for CLIC

We describe a means of producing at train of 40 kA pulses of 3 ps duration as the drive beam for CLIC using an RF–linac driven free electron laser (FEL) buncher. Potential debunching effecs are discussed. Finally we describe a low energy test experiment.

Radiation from wigglers in the low energy ring of an asymmetric B factory

We compute the angular distribution of radiation in the near field of a long damping wiggler that is required to determine the equilibrium emittance and the damping decrement in the low energy ring of a high luminsoity B factory. From the power distribution we can estimate the size of the vacuum chamber, the photon channel, and the photon dump that can tolerate the enormous average power of x‐rays generated in the wiggler.

Design of the vacuum system for the high energy ring of an asymmetric B-factory based on PEP

The multi-ampere current required for high-luminosity operation of an asymmetric B factory lads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. The authors present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9-GeV electron storage ring of the proposed B factory based on the Positron-Electron Project (PEP). The excellent thermal and photodesorption properties of Cu make it possible to handle the high photon flux in a conventional, single-chamber design with distributed ion pumps. The X-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in <500 hr of operation.<<ETX>>

Control of radiological hazards in the UCLA phi factory

Abstract Calculations of the shielding and radioactive inventory produced in a compact, high luminosity phi factory show that such a facility presents a sufficiently low hazard to be consistent with location in a densely populated campus environment.