1. Luminosity Monitor Status
MICE Collaboration Meeting
5 November 2009
Paul Soler

2. Purpose of Luminosity Monitors
Luminosity monitor to determine particle rate close to target and extract protons on target as function of depth – independent of beam loss monitors.
Luminosity monitor will record the number of particles crossing 4 scintillators for every spill – can build up high statistics to validate particle production in target.
By having a small plastic filter we can also reduce low energy protons – some sensitivity to proton energy.
Can be used to compare particle rates close to target (luminosity monitor measures mainly protons and pions) with other counters along beamline (GVA1, TOF0, CKOV, TOF1 and FBPM counters which measure pions, muons, electrons) – validate beamline simulations
For this reason, the luminosity monitor will be very useful for beam commissioning
P Soler, MICE CM25,
5 November 2009

3. Purpose of Luminosity Monitors (cont.)
Validation of beamline simulations
Comparison with beam-loss monitors to determine protons-on-target (pot) and cross-correlate BLM calibrations
BLM calibrations as function of KE:
P Soler, MICE CM25,
5 November 2009

4. Particle Counters in 2006
We already did particle monitoring during first target test in November 2006: two sets of detectors at 10 m distance, 30o angle (where D1 is now)
1 pair of shielded scintillators: 3x3x30 mm3
(with 5 cm polyethylene shielding)
1 unshielded pair of detectors: 10x10x10 mm3
Scope DAQ and readout to Linux PC via GPIB
Signals from scintillators and ISIS
were read out and recorded using
oscilloscopes for each burst
Discrimination and coincidence
of signals performed offline
Position of detectors
(same angle as MICE beam)
Unshielded detectors
All described in
MICE-NOTE-227
P Soler, MICE CM25,
5 November 2009

5. Data taking Nov 2006
Number of particles recorded by detectors during last 2 ms of spill (KE= MeV) when target expects to dip in beam
Correlation between beam loss and number of particles in last 2 ms of spill recorded by detectors
Unshielded detectors
Shielded detectors
50 mV integrated beam loss signal corresponds to 2.8x109 protons on target (calibration: 3.5x10-14 V s/proton at 9 ms with ~50% error)
P Soler, MICE CM25,
5 November 2009

6. MARS Distributions at Scintillator Plane
Number particles
Simulations: 10 Million protons on MICE target, KE = 800 MeV (from 2006)
Number particles
Unshielded
5 cm polyethylene shielding
P (MeV/c)
P (MeV/c)
MARS yields in simulated area of 40x40 cm2 at 10 m distance
P Soler, MICE CM25,
5 November 2009

7. GEANT4 Distributions at Scintillator Plane
Number particles
Simulations: 10 Million protons on MICE target, KE = 800 MeV (from 2006)
Number particles
Unshielded
5 cm polyethylene shielding
P (MeV/c)
P (MeV/c)
GEANT4 yields in simulated area of 40x40 cm2 at 10 m distance
P Soler, MICE CM25,
5 November 2009

8. Back of envelope calculations
For example, let’s take beam loss of 50 mV:
From MARS simulation at 800 MeV:
So, the expected number of singles in 1 cm2 is:
So, most particles observed in target test were protons
Found agreement between MARS, GEANT4 and data
If we want to discriminate integrated proton flux above some energy threshold then introduce shielding between first pair and second pair scintillators
(in last two milliseconds)
(compare to observed rate in slide 5)
P Soler, MICE CM25,
5 November 2009

9. Proposed design of Luminosity Monitors
Final design of luminosity monitor:
Rate: for beam loss monitors running 50 times higher level (ie. beam loss ~2.5 V) would mean around 2000 particles/cm2 in final 2 ms of spill (ie ~4 MHz proton rate in 4 cm2)
Cuts off: protons ~500 MeV/c pions ~150 MeV/c
Beam
P Soler, MICE CM25,
5 November 2009

10. Photomultipliers PMTs: Hamamatsu H5783P 0.8 ns rise time ~1x106 gain
Only need to provide 15V to power PMT
Cost: £632/PMT. Had two already, only needed to buy two extra (~£1300)
Readout: use NIM coincidence units and count three channels using VME scalers already in DAQ
50 mm
High rate capability with
10 ns coincidence gate
If rate still an issue, can
make more shielding
P Soler, MICE CM25,
5 November 2009

11. Status Luminosity Monitor
The box with four scintillators+PMTs is ready
Was going to install during shutdown on 26 October but communication with MICE-OM and management was not optimum to schedule installation, so decided to delay until next shutdown
Biggest challenge: need to install RG58 cables (8 x 50 m between ISIS and MICE counting room) through synchrotron vault – coordinate with ISIS, MICE-OM and Willy
Also coordinate stand for luminosity monitor.
Can have luminosity monitor ready for run in new year
Independently: MSci project student to work on simulations and final analysis of luminosity monitor data in MICE
P Soler, MICE CM25,
5 November 2009