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Advanced Timing and Particle Identification System for TOF II

This system utilizes MICE Liquid H2 absorbers or LiH to eliminate muons that decay and tracks particles using TOF detectors. It features precise timing, pion/muon identification, and compensation coils for accurate measurements. The system also includes solenoids, spectrometers, and RF cavities.

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Advanced Timing and Particle Identification System for TOF II

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  1. TOF system in MICE Liquid H2 absorbers or LiH ? SC Solenoids; Spectrometer, focus pair, compensation coil Electron ID Eliminate muons that decay Tracking devices 201 MHz RFcavities T.O.F. II Precise timing T.O.F. 0 & I Pion /muon ID precise timing • Trigger • PID • Timing respect to RF MB TOF 0, I-II positions

  2. Tof detector structure • Conventional fast scintillator bars, read by PMTs at both ends, arranged in planes (Y or X/Y for better performances) for 3 stations: T0,T1,T2 • Aimed performance  70 ps • Bars are staggered and overlapped at the edges (for cross calibrations with incoming particles) • Calibration: beam particles impinging on overlaps + dedicated fast laser system (a la Harp) MB

  3. A layout of the Laser calibration system (Harp system) Laser Nd-YAG with passive Q-switch (dye), active/passive mode locking and 10 Hz repetition rate IR emission converted to a second harmonic (l=532 nm) by a KD*P SHG crystal Pulse: width 60 ps energy 6 mJ • Beam splitter: • To ultra-fast (30 ps rise/fall) InGaAs MSM photodiode = START • To detector slabs through custom-made optical fibre system = STOP Foreseen mod: introduction of an optical switch to deliver signal to single channel MB

  4. Main experimental problems: • T0: high incoming particle rate (at least some MHz). Solution: R4998 PMTs with modified divider circuit (it can sustain up to 1.6 MHz, but small tolerance to B fiels) • T1,T2: high magnetic fields. Solution: global iron shield+ fine-mesh PMTs (R7761, R5505) • Tests under way: laboratory rate tests for PMTs, fine-mesh PMTs tests in B field MB

  5. PMT rate studies R4998 with modified divider circuit: booster for last dynodes Lab rate tests to be done with: • Hamamatsu PLP-10 fast laser (35 FWHM, 1Hz-1MHz rate, 415 nm) • Fiber launching system into IR multimode fiber (Ceram OPTEC UV 50/100, measured spread 15 ps/m) • PMT signal read by QVT (35 ps resolution) Nominal: up to 1.5 MHz MB

  6. Preliminary rate effects tests • Please insert here .prn file available MB

  7. PMTs for TOF1,TOF2: problems with high magnetic field Fine-mesh PMTs may not be enough • Figure shows |B| from the cooling and measurement solenoids. • The phototubes are placed in a place with high field. • B may be bigger than 1 T -> problems TOF II ? MB

  8. First step: global soft iron shield for downstream detector (GG) MB

  9. Solution from Ghislain: single iron slab 15-cm thick with a central hole of 40 cm-diameter r (cm) B is greatly reduced well below 1 T No problem for PMTs Z (cm) O Field map covers the domain 0 < z < 135 cm and 0 < r < 100 cm (dashed rectangle) MB

  10. Second step: systematic fine-mesh PMTs test in B-field (up to 1.2T) PMT under test Light source: Laser diode Hitachi DL3038-011 (635nm) pulsed by a pulser (Lecroy 9210, risetime 300 ps) FWHM laser pulse 300 ps. Injection in a short optical fiber to a prism, giving light to the PMT Output PMT signal to a Silena QVT MB

  11. Fine-mesh phototube Properties Under test MB

  12. Test magnet at LASA. First typical results. • Timing measurements • Gain measurements • As a function of B, • More measurements under way MB

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