SCH: LEADE LPM+AG 15/12/031 Non intercepting diagnostics based on synchrotron light from a bending magnet (started as “piggy back” on transverse profile system) Longitudinal Beam profile (3564 bunches) Abort Gap Population Bunched/Debunched beam at injection Empty RF Buckets (aka “ghost bunches”) Longitudinal wings (high resolution) Core Measurements: length, distribution, oscil.. Functional Specification: CERN/EDMS Doc LHC- Longitudinal Profile Monitor.

SCH: LEADE LPM+AG 15/12/032 Point 4: Echenevex RF accelerating cavities

SCH: LEADE LPM+AG 15/12/033 Specification Requirements MODE Ultra-high sensitivity High sensitivityStandard sensitivity Sensitivity (p/ps) Sensitivity/Ult. Peak Density3x x x10 -3 Dynamic range (p/ps)60 to 6x10 4 6x10 4 to 3x10 8 5x10 6 to 5x10 8 Sampling period 100 ns50 ps Integration time100 ms10 s1 ms Accuracy  30 p/ps  4x10 3 p/ps  1% Transmission rate< 1 s1 min100 ms APPLICATIONS Abort gap monitorX Tails X Ghost bunches X De-bunched beam X Core parameters X

SCH: LEADE LPM+AG 15/12/034 Longitudinal Profile Monitor: situation Sept LPM is a LARP contribution/“collaboration”, not in-house project LPM is studied by Berkeley lab, (need similar instrument in ALS) (n.b. same group responsible for LHC Luminosity measurement) Initial plan: 2002 R&D (APD/ Laser mixing) 2003 Choice of technology + Prototype design 2004 Production electronics and instruments 2005 Install in LHC (2006 reserved for transverse instruments)

SCH: LEADE LPM+AG 15/12/035 Undulator and D3 magnet at LHC Point 4 Light production at injection energy too low: SC undulator added

SCH: LEADE LPM+AG 15/12/036 Abort gap, 3  s For Ions: spacing 100ns, total 890 bunches, 1:40 RF cycles (Protons)

SCH: LEADE LPM+AG 15/12/037 LHC Beam profile 3564 bunches+ 32,076 empty buckets, RMS Bunch length 0.28ns: sample time 50 ps 89  s/50ps = 1,780,000 data bins…. Integrate over 40ms… …50,000,000 data points/second

SCH: LEADE LPM+AG 15/12/038 Fast Photon Detectors: Commercial Avalanche Photodiode modules PC card for Time-correlated Single Photon Counting: TimeHarp 200 3MHz count rate, <40ps resolution …but only 4096 time-bins…

SCH: LEADE LPM+AG 15/12/039 Fast Photon Detectors: Avalanche Photodiodes 100ps, 16 bins C-SPAD: Cooled Single-Photon Avalanche Diode With active quenching circuit: laser range-finding of satellite in flight, T.Otsubo, CRL, Tokyo

SCH: LEADE LPM+AG 15/12/0310 Photon Counting: MCP PMT Hammamatsu R3809U Photon counting has its problems too, For high dynamic range, there must be no systematic false counts

SCH: LEADE LPM+AG 15/12/0311 MCP-PMT: Dynamic range 900 ns 10 2 Self-generated false counts after event: need to gate detector off for 1us after each event: count rate drops to 10’s of kHz.

SCH: LEADE LPM+AG 15/12/0312 Proposed Laser Mixing System: Synch light, 633nm 40 MHz Laser Ti:Sapphire 800nm filters Mixing crystal 8 bit Detector 350nm Very narrow light spectrum is used, ~3nm (1% of available) Laser pulse timing phase-locked to Machine RF, with offset Laser used to sample with 10ps pulses at 40MHz Max. Data rate at laser frequency, could be 80MHz?

SCH: LEADE LPM+AG 15/12/0313 Laser Mixing: LPM High Sensitivity Mode 400MHz Bucket 2.5ns 25ns laser sample interval, 500 sample points/scan Increment delay by 50 ps / machine rev If PMT is 1% accurate, still need to integrate over 1000 samples to get spec accuracy: 55s + settling time ( Spec in 10s )

SCH: LEADE LPM+AG 15/12/0314 Compress Scale... SET3

SCH: LEADE LPM+AG 15/12/0315 LM Concerns: Low wavelength conversion efficiency - single photon counting - needs longer integration time Requires exclusive operating modes -std/high resolution modes High res. integration time too long: - 10 sec: increase to 1min

SCH: LEADE LPM+AG 15/12/0316 LM system is unlikely to meet specs for integration time, and is not suitable for abort gap protection (too complex) If LM system is used, 3 separate instruments will be needed. Avalanche Photon counting has its problems too: as the count rate reduces, the number of detectors becomes large. No work is being done on the APD method.

SCH: LEADE LPM+AG 15/12/0317 Photon Production and the Abort Gap Monitor Calculated photon production ( nm) : photons/proton at the extraction mirror (…& ions?) At injection energy, abort level is now x700: 60p/ps x 700 = 5.88^6 photons/100ns/turn = 6 10^9 photons / 100ms integration The 7TeV abort level remains at 60p/ps: photons/integrated over 100ms =0.3nJ signal (n.b.this is corrected from the value given in talk, the D3 bending magnet is more efficient at 7TeV) From this must be taken transmission losses, detector efficiency(10%), bandwidth(1%), background noise…

SCH: LEADE LPM+AG 15/12/0318 Abort Gap monitor is important machine operating instrument; needs simple robust solution. A separate instrument is considered. 2003: LARP priority for LPM reduced, no funding given (no work done) LBNL team concentrates on Luminosity. 2004: LDM priority raised: ¾ FTE available for LPM+AG (no material) Priorities now set: 1/ Abort Gap monitor 2/ Luminosity 3/ LPM (R&D tool?) To increase the reliability/availability and performance of the AG and LPM, separate, warm undulators are considered, cost and initial design for March ‘04

SCH: LEADE LPM+AG 15/12/0319 AG Tests at the ALS Bunch spacing 2 ns Bunch width ~50 ps “Camshaft” pulse 328 RF buckets filled ~120 ns gap (LHC parameters) (2808/35640) ( ps) (2.5 ns) (3.3 µs)

SCH: LEADE LPM+AG 15/12/0320 Hamamatsu R5916U-50 Photomultiplier Tube Gate min. raise time: 1 ns <2.5 ns RF bucket spacing Gate voltage: 10 V Low voltage switching required Gain at –3.4 kV: 10 6 High gain < 10 dark counts/sec Low noise Max duty cycle: 1% 100 ns -> 100 kHz max sampling rate -> 3 ms to measure entire abort gap (w/o integration)

SCH: LEADE LPM+AG 15/12/0321 (Pockels cell) MCP-PMT experimental setup (present) SROC Hamamatsu Streak Trigger Unit HP8114A Pulser MCP PMT Visible Light Stanford DG535 Delay 1.5 MHz~100 kHz 10 V Gate Hamamatsu C3360 HV -3 kV Tektronix TDS754D

SCH: LEADE LPM+AG 15/12/0322 Camshaft Parasitic bunch Regular bunches Empty buckets (gap)

SCH: LEADE LPM+AG 15/12/0323 Gate signal on Parasitic bunch Gate signal on Parasitic bunches Gate signal delayed 28 ns

SCH: LEADE LPM+AG 15/12/0324 The Situation 12/03: Tests to establish Sensitivity and Dynamic range of MCP-PMT …answers for Chamonix? Studies to establish reliable AG design: accessibility, few interventions AG data needed for warm undulator design. More effort should be available in 2005/6 for LPM system: technology choice still open but time very short.