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Monte Carlo simulations for the JEDIpolarimeter at COSY
Paul Maanen on behalf of the JEDI CollaborationJEDI Collaboration | Physics Institute III B, RWTH Aachen UniversityDPG Frühjahrstagung 2016
Outline
Introduction
Detector concept
Simulation studies
Summary & Outlook
March 18, 2016
2/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Motivation
Where is the Antimatter in our Universe?
• One precondition for Baryogenesis: CP
• Standard Model prediction: nBnBn
1018
• WMAP and COBE (2012): nBnBn
1010
)Not enough CP in Standard Modell
H = d ~SS · ~E
d = EDMP : H = +d ~S
S · ~ET : H = +d ~S
S · ~E)Electric Dipole Moments violate CP (assuming CPT ))Probe into the physics of the early universe
March 18, 2016
3/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Nuclear scattering polarimetry
• Nuclear scattering cross section for scattering of polarized particles:(,) = 0() ·
1 + PyAy() · cos()
• Measure left-right asymmetries in cross section: Py = 1Ay
LRL+R
• May need to also include up, down to account for tensor polarization
• Currently using elastic deuteron-carbon scattering
March 18, 2016
4/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Design goals for an EDM polarimeter
• EDM search in storage rings: Let EDM interact with fields, wait for polarizationchange: d ~S
dt / d ~E ~S
• Current candidate method for EDM search implicates a linear buildup ofpolarization with time at P = O(106/1000s)
• Design goals for polarimeter:– Large FoM
– Minimal influence on beam
– High sensitivity to systematic effects
– Good long term stability and reproducibility
March 18, 2016
5/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Target choice
[deg]Θ5 10 15 20 25 30
[mb/
sr]
Ω/d
σd
1−10
1
10
210
310200 MeV270 MeV
Cross-Section
[deg]Θ5 10 15 20 25 30
FOM
[a.u
.]
1
10
210
2y A× σFOM =
200 MeV270 MeV
[deg]Θ5 10 15 20 25 30
yA
0.2
0.4
0.6
0.8
1
Analyzing Power
200 MeV270 MeV
270 MeV: Y. Satou et al. Phys. Let. B 549, 307200 MeV: T. Kawabata et al. Phys. Rev. C 70, 034318
• Carbon was chosen as working choice• Large analysing power, high elastic cross section• FOM for Protons also concentrated in the forward region
March 18, 2016
6/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Detector concept
PL Sci
Fast HCAL
PMT
COSYbeam
Vacuum pipe
Target chamber
March 18, 2016
7/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Signal generation
[deg]Θ5 10 15 20 25
[MeV
]dE
260262264266268270272274276278280
C12C(d,pn)12
[MeV]nE0 100 200 300
[MeV
]pE
0
50
100
150
200
250
300C12C(d,pn)12
• Elastically scattered deuterons retain almost complete beam energy.• Break-up has almost no analyzing power, so discard it• Protons and neutrons from break-up are energetically well separated)Complete stop of particles provides good signal separation
• Inelastic reactions carry some analysing power, so maybe keep these
March 18, 2016
8/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Candidate Materials: LYSO/Plastic Scintillator
LYSO
Fe + Pl.
LYSO BGO Plastic---------------------------------------------------------------[g/cm3] 7.3 7.1 1.05
Devay [ns] 40 300 2.4
L. Y. % NaI(Tl) 75 25 25
S. Peak [nm] 420 480 420
N ref. 1.82 2.15 1.58
Melt. OC 2050 1050 75
Hygrosc. No No No
Radioact. Yes No No
LYSO
Fe + Pl.
LYSO BGO Plastic---------------------------------------------------------------[g/cm3] 7.3 7.1 1.05
Devay [ns] 40 300 2.4
L. Y. % NaI(Tl) 75 25 25
S. Peak [nm] 420 480 420
N ref. 1.82 2.15 1.58
Melt. OC 2050 1050 75
Hygrosc. No No No
Radioact. Yes No No
LYSO PlasticDensity [g/cm3] 7.3 1.05
Decay [ns] 40 2.4L. Y. % NaI(Tl) 75 25S. Peak [nm] 420 420
N ref. 1.82 1.58Melt. [°C] 2050 75Hygrosc. No NoRadioact Yes No
March 18, 2016
9/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Simulation setup
• Geometry: Single detector element
• Generated 100k events each at Td = 270 MeV,5 < < 20, 0 < < 360
– Signal: 12C(d , d)12C– Background: 12C(d , pn)12C
• FOM / (elel + bgbg)
Ay ,elelel+bgbgAy ,bg(elel+bgbg)
2
March 18, 2016
10/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Lyso scintillators
range [mm]60 61 62 63
rel.
freq.
0
0.05
0.1
0.15
0.2
0.25
deuteron range in lysoConstant 0.3159± 0.1976
Mean 0.66± 61.44
Sigma 0.5261± 0.5184
deuteron range in lyso
lat. displacement x [mm]10− 5− 0 5 10
rel.
freq.
0
0.05
0.1
0.15
0.2
0.25
deuteron lateral displacement in lysoConstant 0.2761± 0.1856
Mean 2.10319±0.08023 −
Sigma 2.189± 2.046
deuteron lateral displacement in lyso
• Chosen detector size of 3 3 10 cm3as starting value
March 18, 2016
11/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Detector response - lyso
[MeV]depE0 100 200 300
rel.
freq.
[%]
1−10
1
10
Edep in lyso
otherneutron (breakup) escapesneutron (other) escapes escapesγ
deuteron escapesno particle escape
• Breakup is main cause of efficiency lossMarch 18, 2016
12/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Detection efficiencies (lyso)
[MeV]cutE0 100 200 300
∈
0
0.2
0.4
0.6
0.8
1
dcelastic detection efficiency in lyso
0%
5%
10%
20%
dcelastic detection efficiency in lyso
[MeV]cutE0 100 200 300
∈
0
0.2
0.4
0.6
0.8
1
dcbreakup detection efficiency in lyso
0%
5%
10%
20%
dcbreakup detection efficiency in lyso
[MeV]cutE0 100 200 300
rel.
fom
[au]
02468
10121416
relative fom in lyso
0%
20%
March 18, 2016
13/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Plastic scintillators
z / mm0 20 40 60 80 1000
50
100
150
200
250
vs z - deuterons in ironkinE vs z - deuterons in ironkinE
range [mm]42 42.5 43 43.5 44
rel.
freq.
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4deuteron range in plastic
Constant 0.5037± 0.3739
Mean 0.39± 43.24
Sigma 0.2810± 0.3565
deuteron range in plastic
• Use degrader to suppress photon background and reduce length of plasticdetector.
• Td = 270 MeV– Absorber thickness 40 mm– Scintillator thickness 50 mm
March 18, 2016
14/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Detector response - plastic
[MeV]depE0 100 200 300
rel.
freq.
[%]
1−10
1
10
in plasticdepE
otherneutron (breakup) escapesneutron (other) escapes escapesγ
deuteron escapesno particle escape
March 18, 2016
15/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Detection efficiencies (plastic)
[MeV]cutE0 100 200 300
∈
00.10.20.30.40.50.60.70.8
dcelastic detection efficiency in plastic
0%
5%
10%
20%
dcelastic detection efficiency in plastic
[MeV]cutE0 100 200 300
∈
00.020.040.060.08
0.10.120.140.16
dcbreakup detection efficiency in plastic
0%
5%
10%
20%
dcbreakup detection efficiency in plastic
[MeV]cutE0 100 200 300
rel.
fom
[au]
0
2
4
6
8
10
12
14
16
relative fom in plastic
0%
20%
March 18, 2016
16/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Results
• Main cause of efficiency loss is breakup in detector
• Maximum relative FOM:
0% 20%Plastic 15.5 14.5LYSO 17 12
• LYSO and plastic scintillators provide comparable performance
• No strong dependence on energy resolution
March 18, 2016
17/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
Summary & Outlook
• We have a candidate layout for JEDI polarimeter
• Simulations suggest promising performance
• Hardware tests with LYSO crystals are in progress
• Will include E E particle identification technique
• Will include inelastic scattering in simulation
March 18, 2016
18/18
Monte Carlo simulations for the JEDI polarimeter at COSY
Paul Maanen on behalf of the JEDI Collaboration
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