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“THE OLYMPUS LUMINOSITY MONITORS” Ozgur Ates Hampton University. *. * Supported by NSF grant No. 0855473. A R eview of the MC S tudies of t he L umi M onitor s Some GEM Reports from PREX at JLAB April 26-27 OLYMPUS MEETING at DESY. Luminosity Monitors: Telescopes. - PowerPoint PPT Presentation
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“THE OLYMPUS LUMINOSITY MONITORS”
Ozgur Ates
Hampton University
1
A Review of the MC Studies of the Lumi Monitors
Some GEM Reports from PREX at JLAB
April 26-27 OLYMPUS MEETING at DESY
* Supported by NSF grant No. 0855473
*
2
Luminosity Monitors: Telescopes
Forward telescopes
12o
2 tGEM telescopes, 1.2msr, 12o,R=187/237/287cm, dR=50cm, 3 tracking planes
TOF
Luminosity monitors for LEPTON in coincidence with Recoil PROTON detected in the opposite sector, and vice versa.
LEPTON
PROTON
LEPTON
PROTON
Control of Systematics
• Forward-angle (high-epsilon, low-Q) elastic scattering (se+ = se-) means there is no two-photon exchange
• Separately determine three super ratios• Left-right symmetry = Redundancy
Triple Super Ratio:Run the Exp. For the “4 different states”i= e- vs e+ j=toroidal magnet polarity(+-) Repeat cycle many times
Ratio of acceptances(phase space integrals)
Ratio of luminosities
Ratio of counts
4
Forward Elastic Luminosity Monitor• Forward angle electron/positron telescopes or trackers
with good angular and vertex resolution• Coincidence with proton in BLAST• High rate capability
• It will be built at Hampton University this year!
GEM TechnologyMIT prototype:
Telescope of 3 Triple GEM prototypes (10 x 10 cm2) using TechEtch foils
F. Simon et al., NIM A598 (2009) 432
Monte Carlo Studies by using Geant4
• Generated and reconstructed variables Theta, Phi, Momentum, Z(vertex)Proton & Electron• Resolutions δZp, δTp, δPhp, δPp, δZe, δTe, δPhe, δPe
• Residuals: Redundancy of variables / elastic scattering• 4 variables: Pe, Pp, Te, Tp• 3 constraints: 3 conservation equations
4 – 3 = 1 (DEGREES OF FREEDOM)
TeTp: Te – Te(Tp)TePe: Te – Te(Pe)TePp: Te – Te(Pp)
• Coplanarity:PhePhp: Phe – Php – 180
• Common vertex:ZeZp: Ze – Zp
6
Resolution: generated - reconstructed
100micron, 50cm, LuMo+BLAST (Te=0-80 dg, Phe=+-15 dg)
δZp δZe
δTp δTe
δPhp δPhe
δPp δPe
7
Resolution: generated - reconstructed100micron, 50cm, LuMo only (Te=6-13 dg, Phe=+-5 dg)
δZp δZe
δTp δTe
δPhp δPhe
δPp δPe
8
9
Residuals: TeTp=Te-TeTp (one sample)
• Many configurations were simulated.• Varied intrinsic res. and distance between tracking
planes.• 100 µm intrinsic res. and 50 cm gap between Gem1/2
and Gem2/3 show the optimum performance. 10
Design Parameters: Resolutions
Left Sec. RESOLUTIONS
Proton DeltaZ
Electron DeltaZ
Proton Del.Theta
Electron Del.Theta
Proton DeltaPhi
Electron DeltaPhi
Proton DeltaP
Electron DeltaP
100mic./50cmLuMo Only
1.70 mm 1.68 cm 0.59 Deg. 0.15 Deg. 0.55 Deg. 0.39 Deg. 21 MeV 78 MeV
100mic./50cmLuMo + MWPC
Imposed1.80 mm 2.11 cm 0.61 Deg. 0.17 Deg. 0.56 Deg. 0.40 Deg. 21 MeV 106 MeV
Conclusions
• 10x10 cm2 GEM detector size for active area at 12 degree.
• Least distance of first element 187cm for clearance
• The second should sit 237cm and third gem 287cm away from the target.
• Elastic count rate still sufficient with 50cm gaps
• 100 µm intrinsic resolutions of GEM’s meet the experimental requirement.
13
Next Steps
• Simulations of phase space integral(s), acceptance; expected counts
• Study of systematic effects (beam offset, slope, width; etc.) on counts per bin
• Simulation of backgrounds
• Build and test the detectors by end of this year!
• Implement in OLYMPUS in 2011, run in 2012 14
The 208Pb Radius Experiment ("PREX")
The X position of a VDC Track projected onto the GEM
This value is about +/- 0.1 (units are m)
GEM Hit Pos vs Projected VDC Pos
Resolutions ~3mm= GEM Hit Pos – Projected VDC Pos on X & Y(UVA & INFN)
ADC Spectrum (Entry<50000)Pedestal and Noise Suppressed
ADC Correlations UVA and INFN
ADC values vs Strips(=248) are fired event by event(=50000)
The size of the reconstructed clusters in strips(140 micron strip pitch) events=50000