What are these Pion Hodoscopes?

They are different scintillar detectors which are used for position and momentum measurements of the pion beam.

What are they needed for?

The pions are produced on a secondary target and therefore white in momentum and angle. The beampipe accepts roughly +-4% momentum spread. But for analysis you need the momentum of the incoming particle with a better resolution.

As the pions have different momentum and angle, the beam focussing is not trivial and need to be checked. Position measurement near the target can tell how good the focus is. In combination with a momentum measurement this is a nice diagnostic tool.

Why not use the existing diamond Start/Veto detector for this?

MIPs - Minimal Ionizing Particles with charge +-1 The diamond wont see them.

Note: the new monocrystal diamond could be an additional solution here.

What type of detectors?

  • 2 detectors with scintillating bars, 16*1cm
  • 1 detector with scintillating bars dunnow the size
  • 2 detectors with 96*1mm scintillating fibers
  • 2 detectors with 64 scintillating strips

Details of the Fiber Detector

Each of the two detectors consists of 96 channels of scintillating fibers. The scintillating fiber is welded to lightguides of the same diameter, which lead to the photomultipliers. Each channel consits of four scintillating fibers whcih run to the same pixel of the PMT, therfore the light is summed up. The readout is done on both sides in coincidence, therefore killing any noise from the PMTs. The PMTs are 16-fold multi-anode PMTs, 4*4 pixels each.

-- BjoernSpruck - 10 Apr 2006
Topic revision: r3 - 2008-03-03, BjoernSpruck
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