1. Peter-Raymond Kettle Tokyo - Topical Meeting, March 2006 1 Beam Monitoring Basis for Discussion only Beam Rate Beam Rate Beam Profile Beam Profile Beam Normalization Beam Normalization

2. Peter-Raymond Kettle Tokyo - Topical Meeting, March 2006 2 Beam Parameters  Available Parameters Phase Space parameters (x, x ’, y, y ’, p,  p) µ + - & e + - intensity R µ, R beam e, R Michel e µ + - & e + - intensity R µ, R beam e, R Michel e µ + stopping fraction R µ stop µ + stopping fraction R µ stop  Primary Parameters for Monitoring/Calibration x, y, R µ, R µ stop x, y, R µ, R µ stop ideal to measure directly & indirectly ideal to measure directly & indirectlyHardwareHardware Michel decays

3. Peter-Raymond Kettle Tokyo - Topical Meeting, March 2006 3 Beam Rate & Profile Indirect possibility: 1. measured by Michel e + reconstruction using TCs & DCs 2. see Normalization (R µ ·  ·A ccp ), (R µ Stop ·  ·A ccp ) (R µ ·  ·A ccp ), (R µ Stop ·  ·A ccp ) & (x 0, y 0 ) & (x 0, y 0 ) Direct possibility (hardware): 1. measure R µ via (x, y& 1. measure R µ via (x, y ) & R APD at centre using R APD at centre using APD-array mounted on inside APD-array mounted on inside of insertion bellows of insertion bellows (i) Bellows Extended: (x 0, y 0, R µ ) – directly (1 per day C-W Calib.) Disadvantage target must be moved – calibration only ! Disadvantage target must be moved – calibration only ! (ii) Bellows Retracted: Michels only ! R Z  R µ - monitoring Disadvantage constant of proportionality must be measured Disadvantage constant of proportionality must be measuredAPDsy xx

4. Peter-Raymond Kettle Tokyo - Topical Meeting, March 2006 4 Beam Rate & Profile - cont. Direct possibility (hardware): - cont. 2. measure R µ ? & (x, yusing fast, extremely thin MWPC 2. measure R µ ? & (x, y ) using fast, extremely thin MWPC R µ via current & calibration, (x, y) via calibration- monitoring R µ via current & calibration, (x, y) via calibration- monitoring (i) only possible at entrance window – no vacuum (i) only possible at entrance window – no vacuum Disadvantages – (x Z, y Z ), radial Bfield component, Disadvantages – (x Z, y Z ), radial Bfield component, > multiple scattering, rate problematic, potential background > multiple scattering, rate problematic, potential background Typical characteristics: (100x100) mm 2, 1mm wire spacing, 2.5mm half-gap (100x100) mm 2, 1mm wire spacing, 2.5mm half-gap x- y-wire planes, 3 cathode foils (12.5µ), 2 shielding x- y-wire planes, 3 cathode foils (12.5µ), 2 shielding foils (25µ) foils (25µ) 70% CF 4 30% i-C 4 H 10 70% CF 4 30% i-C 4 H 10 live Profile readout type, charge integration & clocked live Profile readout type, charge integration & clocked discharge discharge Examples: µLAN (10x lower rate) Examples: µLAN (10x lower rate) MEG profile Chamber (too thick µ + stop) MEG profile Chamber (too thick µ + stop) Typical characteristics: (100x100) mm 2, 1mm wire spacing, 2.5mm half-gap (100x100) mm 2, 1mm wire spacing, 2.5mm half-gap x- y-wire planes, 3 cathode foils (12.5µ), 2 shielding x- y-wire planes, 3 cathode foils (12.5µ), 2 shielding foils (25µ) foils (25µ) 70% CF 4 30% i-C 4 H 10 70% CF 4 30% i-C 4 H 10 live Profile readout type, charge integration & clocked live Profile readout type, charge integration & clocked discharge discharge Examples: µLAN (10x lower rate) Examples: µLAN (10x lower rate) MEG profile Chamber (too thick µ + stop) MEG profile Chamber (too thick µ + stop)

5. Peter-Raymond Kettle Tokyo - Topical Meeting, March 2006 5 Beam Rate & Profile - cont. Direct possibility (hardware): - cont. 3. upstream, backward-pointing scintillator telescope for Michels from µ-decays-in-flight – beam polarization favours backward from µ-decays-in-flight – beam polarization favours backward decays, R µ via calibration R Tel  R µ - monitoring (i) only possibility between (Triplet II-BTS) (i) only possibility between (Triplet II-BTS) ? Disadvantages – potential background due to re-scattering of discarded beam e + from Separator, at collimator system discarded beam e + from Separator, at collimator system 4.Active Target – would be ideal, polystyrene good material C 6 H 5 CH=CH 2 a~ 0.05 polystyrene good material C 6 H 5 CH=CH 2 a~ 0.05 Disadvantages – rate requires segmentation, light difficult to extract Disadvantages – rate requires segmentation, light difficult to extract 5.Active Degrader – only possible at centre BTS (double waist), MS Disadvantages – rate requires segmentation, light difficult to extract, Disadvantages – rate requires segmentation, light difficult to extract, Bfield Bfield

6. Peter-Raymond Kettle Tokyo - Topical Meeting, March 2006 6 Beam Normalization Need signal  R µ Stop 1.Proton Signal accelerator -10 5 counts/mA·s, good monitor, used for normalizing previous mentioned R µ measurements used for normalizing previous mentioned R µ measurements Disadvantage: depends on p-beam centring Tg.E long-term Disadvantage: depends on p-beam centring Tg.E long-term fluctuations ~10%, doesn’t measure µ’s fluctuations ~10%, doesn’t measure µ’s 2.Measurement via Michel e + spectrum (edge) from DCs & TCs Using event Integration & assuming V-A form of spectrum  R µ Stop =  N µ · A ccp – calibration & monitoring  R µ Stop =  N µ · A ccp – calibration & monitoring Advantage: A ccp is same for µ  e  events further “food for thought” necessary… further “food for thought” necessary…