LCLS Conceptual Design Report - Stanford Synchrotron Radiation ...

L C L S C O N C E P T U A L D E S I G N R E P O R T
The attenuator translation stages will provide motion in the X and Y directions with a
precision of < 1 mm.
Diagnostics Tanks
Space is available downstream from the gas and solid attenuators for beam diagnostic
measurements such as pulse intensity and pulse shape. The diagnostics will monitor the operation
of the attenuators. See Section 9.4.2.
Beam Stop with Burn-Through Detector
At the downstream end of the Front End Enclosure there is an insertable beam stop. This
device consists of an upstream beryllium section to reduce the peak power of the FEL beam, and
downstream copper and heavy metal sections to absorb the full spectrum of the LCLS. The beam
stop includes an integral burn-through detector, which, in case the beryllium section fails to
insert, will protect the radiation absorbers and shut down the LCLS. The radiation absorbers are
duplicated with separate control systems so that the risk of a radiation accident is negligible.
Figure 9.9 Concept of the insertable beam stop with burn-through detector.
9.2.2.2 Hutch A1
The first hutch in Hall A (Figure 9.10) will contain optical elements which condition the x-
ray beam for the Hall A experiments. Only one such element will be included in the initial LCLS,
though space is made available for future optics. Hall A is intended primarily for high-intensity
experiments, using the full bandwidth of the coherent FEL beam.
9-14 ♦ — R A Y B E A M T R A N S P O R T A N D D I A G N O S T I C S