HYP Progress Update By Zhao Jin. Outline Background Progress Update.
SoLID Background Update
description
Transcript of SoLID Background Update
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SoLID Background Update
Zhiwen ZhaoUVa
2013/11/08
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Outline
• Intro– Estimation– Method
• PVDIS– Baffle update
• SIDIS– target collimator, target
widow, etc• Todo list
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EstimationPVDIS SIDIS He3 JPsi
Beam 50uA 15uA 3uA
Target LD2 40cm 10amg He3 40cm LH2 15cm
Window Al 2*100um Glass 2*120um Al 2*100umRadiation length (target) 5.4e-2 0.8e-3 1.7e-2
Radiation length (window) 2.25e-3 3.4e-3 2.25e-3
Radiation length (total) 5.6e-2 4.2e-3 1.9e-2
Luminosity (target) 1.27e39 3e36 1.2e37Luminosity (window) 1e37 3.7e36 6e35
Luminosity (total) 1.27e39 6.7e36 1.2e37
Comment baffle target window collimator
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Method
• EM background– Build all parts with realistic material in GEMC, turn on
general Geant4 physics list “QGSP_BERT_HP”, throw electrons into SoLID targets
– Results dominated by low energy photons and electrons. EM process should be fairly accurate
– Hadrons produced also, but not used for later study because Geant4 doesn’t have all necessary crosssections
– Neutrons including low energy ones produced also, hasn’t been used for study yet. (Lorenzo showed Geant4 has similar results with FLUKA)
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Method• Hadron background
– pi/K/p generated from Wiser fit, more accurate at DIS region, but extends to low energy region also
– With a distribution according to crossection and no “weight” factor (by Yuxiang Zhao’s modified “eicRate” code), they are thrown into SoLID from their simulated vertices
– SoLID has realistic material in GEMC and physics list “QGSP_BERT_HP” is turned on. It’s the same condition like in EM background study.
– A lot of secondary hadrons are produced. Also many low energy photons, electrons and neutrons
– The primary particle “kind” always dominates unless it decays like pi0 or Ks where decay products donimates
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Method
• e(DIS) and e(ES)– e(DIS) generated from CTEQ fit by code “eicRate”– e(ES) generated from formula by code “eicRate”– Only have even distribution with a “weight” factor.
Doesn’t have distribution same as crosssection and no “weight” factor yet
– Don’t expect it as a big source of background– But it’s need for energy loss and radiation
correction study
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Code and Result
• Code– https://hallaweb.jlab.org/wiki/index.php/Solid_Ba
ckground• Result– http://hallaweb.jlab.org/12GeV/SoLID/
download/sim/background
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PVDIS, baffle design
• What we have learned– It’s not easy to have code automatically optimize to let
high x e(DIS) pass, block position pions and straight photons at same time
– 6 baffle planes is not enough to reduce secondary pion background to the level trigger can take, 11+1 planes works
– 1st baffle inner radius needs to be large to reduce background like moller electron. We use 5cm now
– Beamline at downstream should have as large opening angle as position
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Baffle Design Method1. Study phi turning from eDIS events at every baffle plate front
face. Allow 96% (2-98% of phi change) of rate weighted events with 0.55<x<0.8 and p>1.5GeV to pass through. This define the opening for a very narrow phi slice of eDIS events from the target
Rate VS phi turning
At 20 blocks of 1st baffle plane
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Baffle Design Method2. Enlarge this opening by 5o where positive leaks
start to appear, expect 40%=5/12 acceptance for these eDIS events
Example of 11 baffle planes
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3. Further block photons (pi0) by adding more blockingAt the last (11th) baffle, negative and neutral mixes with each other at low phi where
high x and high P events are. Block photon here will harm eDIS acceptance at high x
At EC, negative and neutral split well from each other due to the additional flight path. Photon block at EC works better.
Baffle Design Method
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EC photon block• EC coverage R(110,265)cm• EC photon block– 30 of them– R(105-200)cm– 5cm(8*X0) thick lead,
reduce photon energy by 1 order
– We have 19cm in Z between Cherenkov and EC for the photon block and 2 GEM planes Illustration only
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Err_Apv(%)x 0.20-
0.300.30-0.35
0.35-0.40
0.40-0.45
0.45-0.50
0.50-0.55
0.55-0.60
0.60-0.67
0.67-0.80
Baffle in pCDR 0.290 0.304 0.287 0.294 0.319 0.356 0.427 0.468 0.641
Baffle new 0.311 0.310 0.291 0.289 0.309 0.344 0.398 0.426 0.578
EC R(110,250)cm nominal acceptanceAssume 50uA, 40cm LD2Pol_beam 85%, 120 days
No trig cut
• New baffle 0.55x 5deg 5cm, 5555 baffle• Background needs to be re-evaluated• Similar level is expected from its blocking ability
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SIDIS He3
• A pair of Tungsten collimators are optimized to block hadrons from target windows into forward angle detectors
• The acceptance shown with and without the collimator is similar to the SIDIS proposal
• A full background study is done• EC performance is under study.
Single trigger rate will be checked
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SIDIS He3, pi-/e- ratio at detectorNo backgroud (HGCC)
Full backgroud (HGCC)
No backgroud (FAEC)
Full backgroud (FAEC)
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Todo list
Next iteration of • PVDIS: background with new baffle• SIDIS He3: figure of merit check to further
optimize the target collimator• SIDIS proton: study sheet of flame and its
impact on detectors• JPsi: full background study
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backup
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sourceZ(-10,30)cmR(0,3.536)mmfor 5x5mm raster
neutral
negative
positive
Acceptance, Baffle 0.55x5degblock
EC module R(110,265)cmEC photon block (“baffle
3.5degblock”) 30 of them R(105-205)cm Start from 2.8 degree and width 4
degree. 5cm(8*X0) thick lead, hope to
reduce photon energy by 1 order
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eDIS acceptance comparison at EC“0.55x 5deg” and “0.55x 5deg block” has best
acceptance at high x
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eDIS rate comparison at EC“0.55x 5deg” and “0.55x 5deg block” has no low
mom leak which could leads to high trig rate