VH-LowB: Vertical/Horizontal Low Background Insert

Start = M and not (Fv or Lv or Rv)
Stop(Lu) = Lu and Lc and not Lv and not Fv
Stop(Ld) = Ld and Lc and Lv and not Fv
Stop(Ru) = Ru and Rc and not Rv and not Fv
Stop(Rd) = Rd and Rc and Rv and not Fv

There is also a low-background insert for vertical or horizontal (side-access) cryostats. However, the veto system is made more complex by the restricted geometry. There are three veto counters and two sections on each external side counter. The upstream (u) and downstream (d) segments of each side counter may be used to produce separate histograms or combined for a single histogram. (The common coincidence counter Lc or Rc reduces random counts.)

Any of the three veto counters, Left (Lv) Right (Rv) or Forward (Fv), will serve to indicate that a muon has missed the sample. They all veto the M counter.

The upstream segment of the left or right counter is vetoed in much the same way as for the H-LowB: A stop signal requires counts in both external counters, (e.g., Lu and Lc) but not in the veto counter(s).

The downstream segment is treated quite differently: the side `veto' counters (Lv, Rv) are used as coincidence counters while Fv provides the sole veto.

Although forward and backward positron detectors are shown in the diagram, it is not possible to measure forward-backward spectra in low background mode, but only in a simple-muon-veto mode.