1 quartic, a tof for atlas/cms forward protons you didn’t know that atlas+cms had forward protons?...
Post on 21-Dec-2015
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QUARTIC, A TOF for ATLAS/CMS Forward Protons
• You didn’t know that ATLAS+CMS had forward protons?
• FP420 = Forward Protons 420m downstream of CMS & ATLAS (joint R&D project)
• Physics is
p H/WW/ZZ p• Measure p’s with very high precision within 3 mm
of beam• Gives mass and quantum numbers of central state.
Andrew Brandt (UTA) Jim Pinfold (Alberta), Mike Albrow (FNAL)
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Tracker, perhaps 10 layers per station, 3 stations, 3D silicon(edgeless, 10um res., fast, rad hard) .... Hawaii/SLAC + Brunel
TOF counter, quartz fiber Cerenkov + MCP-PMTs
Vacuum mechanics: Detectors in secondary vacuum, space constraints between beam pipes, not room for roman pots. High precision movement (microns), reproducibility, fail-safe.
Funding, approvals, etc.
FP420 Challenges
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n=1 n>>1
Cerenkov Effect
Use this property of prompt radiation to develop a fasttiming counter
particle
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It’s been done!
Can’t put our PMT in 7 TeV beam!
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Preliminary UTA drawing of Mike Albrow’s concept for a fast time resolution Cerenkov counter:
proton
Microchannel plate PMT
Initial design used 2 mm2 rods, but not enough light, this drawing shows
6mm2 rods
QUARTIC
z=c(TR-TL)/2 z (mm) =0.21 t (psec)(2.1 mm for t=10 psec)
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Where do Protons go at 420m
3mm
x<2.5 cm
120 GeV Higgs courtesy Peter Bussey, Manchester (irony of particle physics—easier to get plot of protons from Higgs than single diffraction)
xx
y
x
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GEANT4 Simulation (Alberta)GEANT4 Simulation (Alberta)
• A GEANT4 simulation is well underway (see GEANT4 produced graphics above.
• The detector simulation includes:• Tracking of Cerenkov photons to the MCP-PMT through the medium.• Wavelength dependent refractive index of the medium • Wavelength dependent attenuation of the photons• Wavelength dependent reflectivity of the aluminium reflector• Timing of photons from generation to the MCP-PMT • The effects of coupling grease (if necessary)
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QUARTIC Background Rejection (UTA)1) 2 single diffractive protons overlayed with a hard scatter (1% of interactions have a proton at 420m)
97.4% of events primary vertex and fake vertex from combining proton times more than 2.1mm (1) apart ; 94.8% if 20 psec
2) double pomeron overlayed with a hard scatter
97.8% of time vertices more than 2.1mm apart; 95.6% if 20 psec
3) hard SD overlayed with a soft SD
95.5% of time primary vertex and fake vertex more than 2.1mm apart; 91.0% if 20 psec
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Cerenkov Light in Fused Silica (UTA):
UV is important! 640-650 total pe’s : 130 pe/6mm rod
λ #PE QE #p*Q E Θc n
180-250 1652.6 15.70% 259.5 49.6 1.544
250-350 1148.7 18.00% 206.8 47.8 1.490
350-450 624.7 19.90% 124.3 47.2 1.471
450-550 394.3 11% 43.4 46.9 1.464
550-650 271.1 1.50% 4.1 46.7 1.458
total 638.0
#P ave θc ave L Q E ave #P.ave*QE ave
4161.6 48.8 3.99cm 15.57% 648.0
maybe we should call it Fusstic2
2 2
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# 2 sin( ) 1/pe L c d
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0.01
0.01
Single n=1.52 c=49;7.4% of pe’s in 10 psec21.3% in 50 psec
over including QE1.9% of pe’s in 10 psec19.1% in 50 psec
Preliminary Time Distributions:
50 psec
50 psec
red = totally internally reflected lightgreen = extra light if aluminized
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Next Steps• Preliminary design studies are promising
• Need to learn more about MCP’s; preliminary indications are Burle tubes are currently only option due to size of active area
• Burle 85021 600 has 1.5 mm pixels could give very useful x-segmentation for measuring multiple protons in same detector, but it seems
that best timing using single MCP_OUT channel (1/tube) (Wilma Raso)
• Starting to think about electronics (Alberta)
• Test beam at Fermilab summer 2006