Monte Carlo simulations for the JEDI polarimeter at COSY ...collaborations.fz-juelich.de/ikp/jedi/public_files/usual_event/presentation_v1.pdf · Outline Introduction Detector concept

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



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



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



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



Detector concept

PL Sci

Fast HCAL

PMT

COSYbeam

Vacuum pipe

Target chamber

March 18, 2016

7/18



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



d+C elastic

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



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



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



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



elastic

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



preliminary

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



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



elastic

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



preliminary

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



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



Documents

Monte Carlo simulations for the JEDI polarimeter at COSY ...collaborations.fz-juelich.de/ikp/jedi/public_files/usual_event/presentation_v1.pdf · Outline Introduction Detector concept