BGV meeting 12-Jun-2013 EPFL Massimiliano Ferro-Luzzi 1 Beam-Gas Vertexing as an LHC Beam-Gas Vertexing as an LHC diagnostics device: an diagnostics device: an overview overview Motivation Concept Plamen will give details about design parameters (rates, acceptance, , etc.) Organization More in Bernd’s talk
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Beam-Gas Vertexing as an LHC diagnostics device: an overview
Beam-Gas Vertexing as an LHC diagnostics device: an overview. Motivation Concept Plamen will give details about design parameters (rates, acceptance, , etc.) Organization More in Bernd’s talk. LHC emittance measurement. Neglecting dispersion, the beam size is given by size - PowerPoint PPT Presentation
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Current limitations of LHC emittance monitorsCurrent limitations of LHC emittance monitors
Wire Scanners (WS): cannot be used beyond a given intensity limit (depends on energy), wires break, movable device, not a continuous measurement, saturation effects (need to adjust PMT HV vs beam intensity).
Synchrotron light monitors (BSRT): absolute calibration is difficult, the source point moves during ramp, too small signal for ions at low energy, ...
Beam-gas ionization monitors (BGI): broadening of the profile due to too weak guiding field, distortion, difficult calibration, ...
Luminosity scans: must move the beams at the experiments, measures a convolution of two beam emittances, takes times, ...
See Plamen’s talk at recent WorkshopSee Plamen’s talk at recent Workshop9th DITANET Topical Workshop on Non-Invasive Beam Size Measurement for High Brightness Proton and Heavy Ion Accelerators, 16 April 2013
Can do also: full transverse profiles (not just RMS), ghost charge, relative bunch chargesNon intrusive! No beams moved !
Can do also: full transverse profiles (not just RMS), ghost charge, relative bunch chargesNon intrusive! No beams moved !
Proposal presented at LMC 164 (27/3/2013):... «Steve Myers summarized that in principle the LMC agreed that this was a very important, useful piece of equipment. Frederick Bordry invited Plamen Hopchev and Rhodri Jones to come to the LSC meeting on Friday morning to check the full impact .»
Also presented to and supported by HL-LHC committee.
Proposal presented at LMC 164 (27/3/2013):... «Steve Myers summarized that in principle the LMC agreed that this was a very important, useful piece of equipment. Frederick Bordry invited Plamen Hopchev and Rhodri Jones to come to the LSC meeting on Friday morning to check the full impact .»
Also presented to and supported by HL-LHC committee.
Demonstrator: gas target sketchDemonstrator: gas target sketchgas injection and accumulation
pumping pumping
WF suppression
detector
detector
long (small diameter) pipes act as flow restrictions
ideal pressure profile
z
p
more realistic pressure profile
this must be transparent! (thin)
beam
Reminder: contrary to VELO/LHCb, here gas injection must be continuous (with beam)... Consider impact on machine!Reminder: contrary to VELO/LHCb, here gas injection must be continuous (with beam)... Consider impact on machine!
to be optimized:ratio of useful/total gas integralto be optimized:ratio of useful/total gas integral
Use SciFi/SiPM !Use VELO-like readout (Beetle to Tell1).
Raw gas rates: 50Hz/1011p per meter of 6.4x10-8 mbar NeHence:- full beam (3x1014p)- full gas length (5m)0.75MHz raw rateShould stay <1MHz!!simple activity trigger
Evt size = ~ 17 bits/clus * 10 clus/plane/Evt * 8 planes = 0.2 kB/Evt0.2 kB/evt * 1 kEvt/s = 0.2 MB/s0.2 MB/s * 107 s = 2 TB/year may need to think about nano events...
High Level Trigger: 1 MHz input rate thlt = avge time to take HLT decisionNcpu = nr of CPU cores available in HLT = 100We need to achieve thlt < Ncpu / RL0 = 0.1 ms
Aim: about 200 good events per 1e11p bunch in a few minutes => need about 1Hz good events per nominal bunch
Location: ring 2 , left of IP4Location: ring 2 , left of IP4
~10m~10m
beam 2AA
CC
BB
Detector
Rack
Rack
Approximate distances: A-B = 20m, B-C = 25m Location B for DAQ/CTRL would be better: shorter cables, cheaper (maybe we
have most cables already!) and no uncertainty about CTRL board cable lengths... Can we merge C into B ?? In fact, anywhere in the pink area would be OK (<25m)
Location D: power outlet ? E: network connections ?