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Suggestions by V. Avati and K. Eggert Idea : Crystal placed at 6 s from the LHC beam, deflecting the protons, can improve considerably the proton acceptance of the TOTEM Roman pots Principle lay-out Physics example : Higgs search in central diffraction.
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Suggestions by V. Avati and K. Eggert Idea: Crystal placed at 6 s from the LHC beam, deflecting the protons, can improve considerably the proton acceptance of the TOTEM Roman pots Principle lay-out Physics example: Higgs search in central diffraction Can micro channeling improve the TOTEM experiment Crystal Collimation in Hadron Storage Rings, CERN 7-8 March 2005
ROMAN POT DETECTORS and ELECTRONICS TOTEM APV hybrid Flexible connections (In production) beam Readout chip VFAT Pitch adapter on detector detector Test card for VFAT
(RA LHC MAC 13/3/03) nσ-reach? Detector Distance vs. Beam Detector distance vs. beam is determined by the beam halo. ns = dmin/sx,y(z) 10-15 Expected halo rate: 6kHz (for 43 bunches, Np = 1010, eN = 1mm, ns = 10) Active detector starts at the distance d from the physical edge Closest approach : ns = 10 d = 200mm
Elastic Scattering b* = 1540 m acceptance
p1’ p1 diffractive system X proton:p1’ proton:p2’ P rapidity gap rapidity gap p2 p2’ hmin hmax Example Processes Single Diffraction: X ds/dh p1 proton:p2’ MX2 = xs diffractive system X rapidity gap P Dh =–ln hmin 0 hmax p2’ ln(2pL/pT) p2 Measure leading proton (x) and rapidity gap ( test gap survival). Double Pomeron Exchange: X MX2 = x1 x2 s P Dh2=– ln x2 Dh1=– ln x1 Measure leading protons (x1, x2) and compare with MX, Dh1, Dh2
(1-x2)p -jet gap gap H (1-x1)p h p p -jet MH2 = x1x2 s beam dipole dipole p’ roman pots p’ roman pots Diffractive Higgs Production
220m 420m y(mm) y(mm) x(mm) x(mm) x Dispersion D = 0.08 m D=1.5m Roman Pots in the forward regions Leading diffractive protons seen at different detector locations (b* = 0.5m)
RP stations RP stations Crystal extraction Crystal extraction 6 x beam profile with crystal extraction
Y [m] protons deflected by the crystal the other protons in RP 10 s beam profile X [m] Detector edge Hit distribution in the RP detector
= 15rad Bent by the crystal (by 0.5 mrad) rad Angular distribution in the detector
In Totem acceptance (68% of 1) Totem acceptance with cristal extraction (87% of 1) With cristal extraction 2<1 2<1 -acceptance for a Higgs with MH=120 GeV/c2
Conclusions • Crystal extraction is promising to approach the LHC beams closer than with standard RP detectors • Larger acceptance for diffractively produced Higgs • Same method could be used for elastic scattered protons to reach the Coulomb region Needs extensive tests with crystals and Roman Pots in the SPS (see talk of Marco Oriunno)