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CVD diamonds as beam monitors

CVD diamonds as beam monitors. CVD diamond used for: heavy ion beam monitor beam exit window for primary beams (heat spreader material?) Beam Loss Monitor for CMS. Diamond as beam monitor. Pb 67+ up to 2,5*10 9 Ions pro bunch. Here bunch split into 4 sub-bunches. Diamond signal [V].

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CVD diamonds as beam monitors

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  1. CVD diamonds as beam monitors • CVD diamond used for: • heavy ion beam monitor • beam exit window for primary beams • (heat spreader material?) • Beam Loss Monitor for CMS

  2. Diamond as beam monitor Pb67+ up to 2,5*109 Ions pro bunch. Here bunch split into 4 sub-bunches

  3. Diamond signal [V] Bunch of 2*108 Oxygen ions with beam transformer and diamond strip detector 500ns Beam transformer [mV] Time resolution in sub ns range

  4. Diffusion Bonding: Diamond can be bonded to metal GND HV+Signal Metallization Target (Xenon, 14 bar) Beam Beampipe (Vacuum) Diffusion Bonding Diamond (300um) Flange Contact

  5. Simple sensor design proven in beam Solderpin for cable Vacuumwindow Diamond diffusion bonded in metal vacuum flange diamond • Advantages: • no hybrid needed • radiation hard • mechanically robust • Al-metallization done without • masks • Guard ring = diffusion bond signal 1 cm [V] Left: signals from cyclotron showing the 26 MHz bunches. Each bunch has about 106 protons, so the signal can be directly displayed on the scope without amplifier, even with 10m cable. Width given by spread in bunches 40 ns [ns]

  6. LHC beam loss and background Monitoring at CMS BCM1 IP BCM2 “heat spreader” CVD diamond radhard tunnelcard LHC ionization chambers for beam loss monitoring Beam loss at KA cyclotron

  7. Beam test with BCM electronics for LHC (developed in Bernd Dehning’s group at CERN) 8 channel tunnel cards with optical fiber output 40 us sampling time 16 channel VME readout cards

  8. ADC values CFC Card – working principle Principle: after reset: C is discharged with detector current. To continuously check the card an additional current source of 10 pA discharges as well, so at least every 20s a trigger will be given to a counter indicating that C was discharged below the threshold. Every 40 us the counter on the board is readout telling how many times the capacitor was discharged, which is a measure of the sensor current. Additionally an ADC converts the integrator voltages into digital values which can be used to calculate the slope of the discharge and therefore the current, this is important for low detector currents.

  9. Test at KA cyclotron diamond USB readout electronics CFC-Card current to frequency converter range: 10pA – 1mA low-noise readout radiation hard design sensor signal versus time KAZ Karlsruher cyclotron 26MeV protons

  10. 1scan 5=5scans 36cm 4=4scans 29cm 2=2scans 38cm 3=3scans 31cm System Test at cyclotron in Karlsruhe

  11. BCM at LHC is done by roundabout 3700 gas ionization chambers which are placed round the ring if their signal gets too large a beam dump is requested to prevent a quenching of the superconducting magnets or damage on the machinery there is no space inside the 4 caverns for this chambers, so another solution was needed to monitor the beam without interruption For CMS this is the BeamRadiationMonitoring System consisting of 6 subsystems of which 3 are diamond based and places inside the CMS detector BCM2 consists of 16 (opt 32) pCVD diamonds, which are placed near the beam pipe the readout of BCM2 is solely based on the same electronics as the gas ionization chambers, so the data is immediately available via the LHC software Beam Condition Monitoring at LHC

  12. Tunnel card with CFC from LHC Beam Monitoring Group (Dehning, Effinger) Layout CMS Beam Loss Monitoring

  13. BCM2 sensor • pCVD 350µm 10x10mm • mounted in a box of aluminum for shielding • metalization visible from both sides • contact with bond wires and silver epoxy glue • CMS sensor from Bob Stone, Rutgers • metalization: Tungsten-Titanium • measured CCD: 250µm HV Signal

  14. Decrease of CCD vs fluence with 26 MeV protons

  15. Si Si total C total Si inelastic p Si elastic n C inelastic C elastic C Radiation damage in Diamond Z Ions NIEL 14 417 4.2 13 910 9.06 12 1384 12.47 11 1021 8.86 10 1225 8.45 9 265 1.41 8 493 2.09 7 398 1.31 6 909 2.36 5 270 0.55 4 383 0.66 3 662 0.67 2 11152 4.4 1 46107 0.9 Total 6559 57.38 10 GeV protons Z Ion NIEL 6 698 0.8 5 869 0.77 4 584 0.44 3 1133 0.55 2 10625 2.01 1 30465 0.24 Total 44374 4.81 200 MeV

  16. Radiation monitoring components BCM1 Z=± 1.9m, r=4.3cm BSC Z=± 1.9m, r=4.3cm Cherenkov Fibres Fibre Based Radiation Monitors BCM2 Z=± 14.4m, r=29cm

  17. CMS Flux Maps Charged particle flux at 1034 BCM1 ~ 1x107cm-2s-1 0.25 cm-2 per BX High neutron flux for BCM2 Neutron flux at 1034 BCM1 ~ 1x107cm-2s-1 0.25cm-2 per BX

  18. RADMON CMS Rad mon TOTEM T1 HF Plug TOTEM T2 IP BCM2 Sensors BSC Scintillators (On front of HF) BCM Sensor Carriage+ BCM1 Fibre loop Fibre Coils BCM1 and BCM2

  19. Tracker Bulkhead BCM1 Carriage BCM1 Pixel Rail System Beampipe BCM1: Mechanical Structure

  20. Beam Current Monitors Safe LHC Parameters Current Energy Energy DCCT Dipole Current 1 Injection Kickers SPS Extraction Interlocks Beam Energy Tracking Energy DCCT Dipole Current 2 SafeBeam Flag TL collimators LHC Beam Interlock System Beam Dumping System RF turn clock BLMs aperture BLMs arc Collimators / Absorbers Beam Dump Trigger Access Safety System BPMs for Beam Dump NC Magnet Interlocks Discharge Switches BPMs for dx/dt + dy/dt dI/dt beam current dI/dt magnet current Cryogenics Powering Interlock System essential circuits Screens Quench Protection RF + Damper LHC Experiments auxiliary circuits Vacuum System Power Converters Operators AUG Software Interlocks UPS Timing PM Trigger Machine Protection Systems and Interfaces

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