T980: Crystal Collimation at the Tevatron

Gerald E. Annala¹, Dick Carrigan¹, Alexandre Drozhdin¹, Todd Johnson¹, Young-Kee Kim^1,2, Nikolai V. Mokhov¹, Satomi Shiraishi², Dean Still¹, Richard Tesarek¹

1. Fermilab
2. University of Chicago

About Crystal Collimation

Currently, collimation is performed in two steps in the Tevatron. First, particles in beam halo hits a tungsten target. Interaction of beam and tungsten atoms scatters the particles, where some of them hit a block of steel collimator and be absorbed. However, this method allows only a fraction of scattered particles to be absorbed by the collimator. In order to increase the efficiency of collimation, we study a possible use of a Si bent crystal instead of the tungsten target.

Bent crystal technique has been studied for extracting high energy beams, and we study its application on reducing beam halo in the Tevatron and LHC colliders. By coherently deflecting the beam halo into absorbers via crystal channeling and volume reflection, we hope to reduce scattering of particles and increase efficiency of collimation. The goal for the study at the Tevatron is to use end of store studies to compare the proton halo reduction for existing 2-stage collimation with the conventional tungsten target and the bent crystal.

Demonstration of crystal channeling and volume reflection for a 1-TeV proton beam at the Tevatron is a crucial step in the study. We have an O-shaped crystal placed in the lattice on a lever-arm that we can control the angle and the position with respect to the beam. A PIN diode near the crystal assembly and a beam loss monitor downstream measure the nuclear interaction rate in the crystal and a fraction of the beam deflected or scattered by the crystal.

Beam Diagnostics

E1 scintillation counters

To monitor the loss rate of the beam that are deflected by the crystal, we have installed a telescope at E1. This telescope counts the rate of beam loss at E03 collimator.

Flying Wire

Analysis of flying wire data to study the beam profile before and after the crsytal is inserted.