| Paper | Title | Page |
|---|---|---|
| WEPPD027 | Global and Local Loss Suppression in the UA9 Crystal Collimation Experiment | 2561 |
|
||
|
UA9 was operated in the CERN-SPS for some years in view of investigating the feasibility of the halo collimation assisted by bent crystals. Two-millimeter-long silicon crystals, with bending angles of about 150 mirrored, are used as primary collimators. The crystal collimation process is obtained consistently through channeling with high efficiency. The loss profiles in the area of the crystal-collimator setup and in the downstream dispersion suppressor area show a steady reduction of slightly less than one order of magnitude at the onset of the channeling process. This result holds both for protons and for lead-ions. The corresponding loss map in the accelerator ring is accordingly reduced. These observations strongly support our expectation that the coherent deflection of the beam halo by a bent crystal should enhance the collimation efficiency in hadron colliders, such as LHC.
for the UA9 Collaboration |
||
| THEPPB011 | Apparatus and Experimental Procedures to Test Crystal Collimation | 3254 |
|
||
|
UA9 is an experimental setup operated in the CERN-SPS in view of investigating the feasibility of halo collimation assisted by bent crystals. The UA9 collimation system is composed only of one crystal acting as primary halo deflector and one single absorber. Different crystals are tested in turn using two-arm goniometers with an angular reproducibility of better than 10 microrad. The performance of the system are assessed through the study of the secondary and tertiary halo in critical areas, by using standard machine instrumentation and few customized equipments. The alignment of the crystal is verified by measuring the loss rate close to the crystal position. The collimation efficiency is computed by intercepting the deflected halo with a massive collimator or with an imaging device installed into a Roman Pot. The leakage of the system is evaluated in the dispersion suppressor by means of movable aperture restrictions. In this contribution the setup and the experimental methods in use are revisited in a critical way and thoroughly discussed. Particular emphasis is given on feasibility, reproducibility and effectiveness of the operational procedures.
For the UA9 Collaboration |
||