E. R. Gray

A 200-MHz Debuncher for the Fermilab Injector

Although the momentum spread of the beam as it leaves the linac is comfortably within the design specifications, space charge effects in the 200-MeV transport line and in the booster increase the momentum spread of the debunched beam.112,314 The phase space density of the beam is further decreased during capture in the booster because the magnetic field is changing during capture and because the capture process is not completely adiabatic. 5,6

Reappearance of Linac Bunch Structure on Booster Bunches during Capture and Acceleration

During adiabatic capture and initial 30 MHz beam bunching in the Fermilab Booster very high frequency structure is observed on the bunches. The structure has the appearance of a bunch shape oscillation instability which appears and disappears in a sporadic manner. A computer simulation of injection dynamics reveals the fact that the observed structure is related to re-appearance of the injected linac bunch structure after relocation within the booster phase space.

Injection, Magnet, and Vacuum Systems for the Fermilab Antiproton Cooling Ring

This paper gives construction details of the dipole and quadrupole magnets, a brief description of the proton injection line, and a short report of the vacuum system design for the existing Fermilab Cooling Ring.

Phase space cooling and PP colliding beams of fermilab

It has recently been suggested1 that the present high energy synchrotrons at CERN and Fermilab could be operated as pp storage rings with a center-of-mass energy of some 800 GeV. The Fermilab Energy Doubler/Saver, in addition, would be quite suitable as a high performance storage ring, producing collisions at 2 TeV in the center-of-mass. In order to achieve useful luminosity it is necessary to: 1) collect antiprotons from ˜-80 GeV protons colliding on a stationary target, 2) cool the phase space of the initially diffuse ps, and 3) accumulate the cooled ps over cycles. Several methods have been devised to carry out this repetitive accumulation and cooling. 2,3,4

Longitudinal Beam Motion in the Fermilab Booster Accelerator

The intensity of the Fermilab booster accelerator has been limited in part by longitudinal effects. These include longitudinal space charge blowup prior to RF capture, phase space dilution during capture and insufficient voltage to provide bucket area to accelerate the diluted beam. Measurements of beam properties under these conditions, as well as high intensity effects during acceleration, are presented.

Transverse Beam Motion in the Fermilab Booster Accelerator

Measurements are presented of the transverse properties of the booster synchrotron. The principal transverse limitations to operational performance have been due to restricted aperture and improper multiturn injection. In addition to these features, working point, chromaticities, high-intensity effects, and injection matching are discussed.

Initial Performance of the NAL 200-MeV Linear Accelerator

The first three months of operation of the NAL linac after first achieving a 200-MeV beam have been encouraging. The design performance has been achieved at beam intensities of about 20 mA both in the transverse emittance and the momentum spread. Attempts have not been made to go to intensities of 100 mA or greater as yet, and it will be interesting to see how the beam quality is affected by intensity. It is expected that when the linac rf phase and amplitude controls are properly working, the beam quality will be less than the design values. In particular, the momentum spread at the present operating currents is sufficiently small so that a debunching cavity currently is not envisioned. The beam measurements made so far confirm the theoretical results obtained with the PARMILA dynamics program. The particle distributions used in the program are those measured at the entrance to the linac. The large number of components in the systems have lead to concern over the reliability of the linac. The performance over the last three months has dispelled some of this concern. As running periods have increased the failure rate has decreased. Only two major problems stand out at this time. The first is the failure of the spring contacts on the filament leads to the power amplifier tubes. Installation care and the elimination of two of the contact rings which were not water-cooled seem to be providing at least a temporary solution.

Injection Methods in the Fermilab Booster

At present there are two working injection methods; single-turn using a ferrite kicker magnet and multiturn using a pulsed set of 4 dipoles in one straight section. The operating characteristics of these methods are described. The expected implementation of H injection will involve the incorporation of devices for all three methods in one 6-m long straight section. The H-scheme is described and the expected operating characteristics compared to the present methods.