Beam Position Monitors MICE CM Harbin January, 2009

Beam Monitors  Small (20 X 20 cm)  Large (45 X 45 cm)

Fiber Planes  Active detector is Kuraray scintillating fiber (blue)  Fiber planes are doublet structure like fiber tracker

Material Budget 4 X 0.9 X 0.7 mm polystyrene

Fiber Mapping Small: 64 ch – 3 fiber wide Large: 16 ch – 3 fiber wide 48 ch – 8 fiber wide

Fiber Connector

Small BPM Fiber Planes

Commissioning Status  The Electronic Noise that was seen has now been completely removed u Cable shielding  Both BPMs have been calibrated to some extent with a 60 Co source u However the activity was so low that we had some difficulty  Final calibration with beam was, unfortunately, not done due to the Target failure in December  We did get some beam data with the small BPM, however

Beam Data in Small BPM  Beam data from November run  Dip if Y profile we believe is now fixed after we did the threshold scan/set using the 60 Co source  Once we have beam again, we will continue the calibration (both threshold and PMT HV)  We have also asked for a stronger (100X) 60 Co source

Small BPM Beam Data II

Conclusions  Both the small and the large BPM are working well u No dead channels u Electronic noise rate is ZERO u PMT noise is low - <<1 hit/channel  The small BPM has taken beam data u At that time there was a dip in the response in the Y view s We believe that this is now fixed by adjusting thresholds  The large BPM has been calibrated with the 1  C 60 Co source u It has not seen beam yet  Look forward to doing final calibration with beam in May?  Will also do addition calibrations with 60 Co, if we can get a 100  C source