Muon Veto Insert - sample region

 image of sample region]    

a      Fibreglass shell (blue)
b      Thin muon scintillator (violet)
c      Copper sample frame (orange)
d      Sample (red)
e      Veto scintillator (violet)

This drawing shows a cross section near the end of the insert tail in the region of the sample.

The fibreglass shell (a; shown in blue) and its two inner dividing walls are cut away (blue outline) to allow free muon passage.

The muon enters (through the cryostat window) from the left, passes through a thin, 0.25 mm, scintillator (b; violet) triggering the data acquisition.

The sample (d; red) is mounted in the center between thin Mylar sheets stretched around the square copper frame (c; orange). This structure forms the end of the removable sample rod.

If the muon strikes the sample, it starts both the clock and the pile-up gate, but if it misses and strikes the veto counter (e; violet), only the pile-up gate is started, and that muon is rejected.

The outside of the sample frame is 3.81 cm (1.50 inch) square by 0.16 cm (0.0625 inch) thick, and the central opening is 3.17 cm (1.25 inch) wide by 2.86 cm (1.125 inch) long. Other sample holders may be mounted.

( width × thickness )

Smallest sample: ~0.5 cm × 0.2 mm (A ‘soft’ limit indicating where the good event rate becomes noticably low, and the inefficiency of vetoing is noticable too.
The minimum thickness depends on the sample density and muon momentum.)

Widest sample: 3.1 cm × 0.75 cm (Width limited by sample frame, thickness by compartment.)

Thickest sample: 2.2 cm × 1.3 cm (Width and thickness limited by widest part of sample compartment.)

Intermediate sample: 2.6 cm × 1.0 cm (Maximum sizes interpolate linearly between the previous entries; this entry gives the maximum width for a 1.0 cm thick sample.)

Maintained by Donald Arseneau,