Tagging the EMC effect in d(e, e ′N) reactions

using the BAND and LAD detectors at JLab12

Axel Schmidt

MIT

July 5, 2017

LNSLaboratory for Nuclear Science

1

The EMC effect still puzzles.

0.8

1

1.2

0.25 0.5 0.75

SLAC data (1994)

2σC12σd

x

J. Gomez et al., PRD 49 4348 (1994)

Miller + Smith, PRC 65 015211 (2001)

2

The EMC effect still puzzles.

0.8

1

1.2

0.25 0.5 0.75

SLAC data (1994)EMC slope: 0.32

2σC12σd

x

J. Gomez et al., PRD 49 4348 (1994)

Miller + Smith, PRC 65 015211 (2001)

3

The EMC effect still puzzles.

0.8

1

1.2

0.25 0.5 0.75

SLAC data (1994)EMC slope: 0.32

Fermi-motion

2σC12σd

x

J. Gomez et al., PRD 49 4348 (1994)

Miller + Smith, PRC 65 015211 (2001)

4

Classifying EMC Models

NucleonMotion

MediumModification

All nucleonsmodified slightly

A few nucleonsmodified a lot

EMC Models

Insufficient

5

Theories identify virtuality as the key

to producing EMC-like modification.

Binding RescalingPoint-like Configuration

Suppression

Bound

Free

Bound

Free

Bound

Free + ε

+ ε

A - 1

6

Theories identify virtuality as the key

to producing EMC-like modification.

Binding RescalingPoint-like Configuration

Suppression

Bound

Free

Bound

Free

Bound

Free + ε

+ ε

A - 1

7

Theories identify virtuality as the key

to producing EMC-like modification.

Binding RescalingPoint-like Configuration

Suppression

Bound

Free

Bound

Free

Bound

Free + ε

+ ε

A - 1

8

The EMC effect correlates with

the density SRC pairs.

−0.1

0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4 5 6

2H

3He

4He

9Be

12C

56Fe

197Au

EM

CSl

ope

(−dR/dx B

)

SRC-pair density (a2)

9

Two upcoming experiments will test

the EMC-SRC connection.

Deep inelastic scattering with a recoiling nucleon:

scatteredelectron

jet from struck quark

Deuterium

LAD

11 GeV e–

SHMS

HMS

GEMsspectatorproton

JLab Hall C

scatteredelectron

jet from struck quark

Deuterium

Spectatorneutron

BAND

11 GeV e–

CLAS12

JLab Hall B

10

The Correlations group •  MIT (Or Hen): – Barak Schmookler

– Reynier Torres

– Efrain Segarra

– Afro Papadopoulou

– Axel Schmidt

– George Laskaris

– Maria Patsyuk

– Adi Ashkenazy

TAU (Eli Piasetzky): – Erez Cohen

– Meytal Duer

–  Igor Korover

•  ODU (Larry Weinstein): – Mariana Khachatryan

– Florian Hauenstein •  UT Santa Maria (Chile)

IñakiVega

I will cover:

1 Recoil-Tagged DIS

Testing the SRC-EMC connection

2 The ‘LAD’ Experiment

Large Acceptance Detector

3 The ‘BAND’ Experiment

Backward Angle Neutron Detector

12

I will cover:

1 Recoil-Tagged DIS

Testing the SRC-EMC connection

2 The ‘LAD’ Experiment

Large Acceptance Detector

3 The ‘BAND’ Experiment

Backward Angle Neutron Detector

13

Recoil-Tagging: using a high-momentum recoil to

determine the virtuality of the struck nucleon.

ee'

14

Recoil-Tagging: using a high-momentum recoil to

determine the virtuality of the struck nucleon.

ee'

recoilingspectator

15

Short-range correlations are universal.

-1

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1

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pn(GeV /c)

cos�

5.9 GeV/c, 988.0 GeV/c, 989.0 GeV/c, 985.9 GeV/c, 947.5 GeV/c, 94

Recoil neutron momentum [GeV]

Leading

Recoil

�

Parallel

Anti-parallel

High-momentum tail

20% of nucleons

correlated pairs

high-relative momentum

low CoM momentum

J.L.S. Aclander et al., Phys. Lett. B 453, 211 (1999)

A. Tang et al., Phys. Rev. Lett. 90, 042301 (2003)

E. Piasetzky et al., PRL 97 162504 (2006)16

There are some interpretation challenges.

ee'

recoilingspectator

1 relating the recoil momentum to the stuck nucleon momentum

2 rescattering in the nuclear medium

3 accounting for the nuclear remnant

17

There are some interpretation challenges.

ee'

recoilingspectator

1 relating the recoil momentum to the stuck nucleon momentum

2 rescattering in the nuclear medium

3 accounting for the nuclear remnant

−→ Use a deuterium target.

−→ Look at backward recoils.

18

Advantages of deuterium

Struck nucleon had EXACTLY opposite momentum to recoil.

No residual system

Minimal final state interactions.

ee'

recoilingspectator

19

DEEPS showed little FSI at back angles.

(G eV /c)sP

0.3 0 .4 0 .5 0 .6 0 .7

0

1

2

3

(GeV /c)sP

0 .3 0 .4 0 .5 0 .6 0 .7

0

2

4

6

PWIAdata

θqs > 107˚ 73˚ < θqs < 107˚TransverseAnti-Parallel

103 counts

Klimenko et al., PRC 73 035212 (2006)

20

What we want to measure:

F2(x′,Q2, αs)boundF2(x ,Q2)free

≈ σDIS(x′,Q2, αs)bound

σDIS(low x ′,Q20 , αs)bound×σDIS(low x ,Q20 )free

σDIS(x ,Q2)free×RFSI

. Tagged DIS measurement Input ≈ 1

At low x, the EMC effect should be small:

σDIS(low x ′,Q20 , αs)bound ≈ σDIS(low x ,Q20 )free

21

What we want to measure:

F2(x′,Q2, αs)boundF2(x ,Q2)free

≈ σDIS(x′,Q2, αs)bound

σDIS(low x ′,Q20 , αs)bound×σDIS(low x ,Q20 )free

σDIS(x ,Q2)free×RFSI

. Tagged DIS measurement Input ≈ 1

At low x, the EMC effect should be small:

σDIS(low x ′,Q20 , αs)bound ≈ σDIS(low x ,Q20 )free

22

What we want to measure:

F2(x′,Q2, αs)boundF2(x ,Q2)free

≈ σDIS(x′,Q2, αs)bound

σDIS(low x ′,Q20 , αs)bound×σDIS(low x ,Q20 )free

σDIS(x ,Q2)free×RFSI

. Tagged DIS measurement Input ≈ 1

At low x, the EMC effect should be small:

σDIS(low x ′,Q20 , αs)bound ≈ σDIS(low x ,Q20 )free

23

Different models predict different F2 ratios.

0.2

0.3

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0.5

0.6

0.7

0.8

0.9

1

1.1

1 1.1 1.2 1.3 1.4 1.5 1.6

PLC suppression

Rescaling

Binding

Bou

ndF2

/Fr

eeF2

αs

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1 1.1 1.2 1.3 1.4 1.5 1.6

Melnitchouk, Sargsian, Strikman, Z. Phys A 359 p.99 (1997)

24

Experimental Requirements

1 DIS kinematics

W > 2 GeV

Q2 > 2 GeV2

−→ 10 GeV beam energy

2 Backward recoil detector

Large acceptance for θqs > 110◦

0.25 < pr < 0.7 GeV

Low x ′ and High x ′ coverage

25

I will cover:

1 Recoil-Tagged DIS

Testing the SRC-EMC connection

2 The ‘LAD’ Experiment

Large Acceptance Detector

3 The ‘BAND’ Experiment

Backward Angle Neutron Detector

26

LAD will detect recoiling spectator protons.

scatteredelectron

jet from struck quark

Deuterium

LAD

11 GeV e–

SHMS

HMS

spectatorproton

JLab Hall C28

LAD is three panels of scintillator bars,

originally from the CLAS-6 ToFs.

4/18/17 6

LargeDoublePanels#2

LargeDoublePanels#1

LargeSinglePanel#3

EMC-SRCDetectorsDetectorsatthedifferentplanesfromTargetPanelsoverlapreducingoreliminaInggap

DetectorSupportstobedesignedtoclearFlexLine

29

LAD Experiment Details

Experiment Large Acceptance Detector

Experiment E12-11-107

Approved for 820 hours

Extended LD2 target

11 GeV e− beam

1036 cm−2s−1

Low x and high x settings

5 panels of 11 bars

1.5 sr at back angles

80◦–170◦

±20◦ out-of-plane

31

The limit will be random coincidence background.

Can be subracted using

“off-time” events

Statistical variation can

drown signal

δN

N=

√S + B

S

0 20 40 60 80 100

Signal

Reconstructued ToF0 20 40 60 80 100

Any reduction in background buys us statistics!

32

Energy deposition in LAD must match velocity.

44

Figure 25: Energy loss versus TOF.

To reduce the large singles rates we will set the detector threshold in the first layer of scintillators for protons at 20 MeVee (twice the minimum ionizing energy deposit). We will set the detector threshold in the subsequent layers of scintillators for neutrons at 5 MeVee. I.4 Nucleon momentum resolution The best momentum resolution is obtained by calculating the TOF per meter. From the CLAS operational experience, we know that the time resolution for the large angle counters is 200-250 ps. For detectors at about 5 meter from the target and 300-500 MeV/c nucleon

!pp

= !TOFTOF

= 0.250ns(50 " 33)ns

= 0.5 " 0.8%

For recoil protons we can also determine their momentum using the energy loss. Based on experience with BigBite we expect a resolution of about 20 MeV/c.

!pp

= 20MeV/c(500 " 300)MeV/c

= 4 " 7%

33

Energy deposition in LAD must match velocity.

−80 −60 −40 −20 0 20 40 60 80

Signal

Randoms

Rat

e[a

rb.

units]

Momentum (Edep) - Momentum (ToF) [MeV]

34

We plan to add GEMs to assist in vertexing.

scatteredelectron

jet from struck quark

Deuterium

LAD

11 GeV e–

SHMS

HMS

spectatorproton

JLab Hall C35

We plan to add GEMs to assist in vertexing.

scatteredelectron

jet from struck quark

Deuterium

LAD

11 GeV e–

SHMS

HMS

GEMsspectatorproton

JLab Hall C36

Multiple scattering in GEM material

can reduce effectiveness.

0

200

400

600

800

1000

1200

1400

−15 −10 −5 0 5 10 15

σ = 1.3 cm

σ = 1.7 cm

σ = 2.5 cm

Cou

nts

zrec. − ze− [cm]

ThinRegular

ThickRandoms

37

Expected Impact

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1 1.1 1.2 1.3 1.4 1.5 1.6

PLC suppression

Rescaling

Binding

LAD

Bou

ndF2

/Fr

eeF2

αs

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1 1.1 1.2 1.3 1.4 1.5 1.6

38

I will cover:

1 Recoil-Tagged DIS

Testing the SRC-EMC connection

2 The ‘LAD’ Experiment

Large Acceptance Detector

3 The ‘BAND’ Experiment

Backward Angle Neutron Detector

39

DCJLab Hall B

CLAS12

BeamlineSVT

CTOF

SolenoidFTOF

PCal/ECal

LTCC

TorusHTCC

BAND will detect recoiling spectator neutrons.

scatteredelectron

jet from struck quark

Deuterium

Spectatorneutron

BAND

11 GeV e–

CLAS12

JLab Hall B

41

BAND will surround the upstream beamline.

42

BAND will surround the upstream beamline.

43

BAND Experiment Details

Experiment Backward Angle Neutron Detector

Experiment E12-11-003A

Approved for 90 days

parallel with DVCS

Run group I

Extended LD2 target

11 GeV e− beam

1035 cm−2s−1

Currently being developed

5 rows of panels of 21 bars

160◦–170◦

≈ 60% azimuthal coverage

44

BAND must respect several constraints.

Material in the n flight path

Only 160◦–170◦ is clear

Narrow “Keep-In” Zone

Must be thick to have

high-efficiency (> 30%)

Segmentation aids in pathlength resolution

. . . at the cost of light yield

A

B

C

D

C

Scintillator length● 3 groups for long bars● 1 group for short bars (500 mm)

18 rows & 5 layers (256 PMTs)● 232 PMTs main detector● 24 PMTs veto layer

Keep in zone

BAND design June 7th, 2017 (evening update)

Lengths inside keep in zone● ~28 mm from sides● ~72 mm from beampipe

Scintillator section:74x74mm2

45

We are studying PMT performance at MIT.

ANDOR

TriggerAND

60Co Source

Reference Bar

Test Bar

Efrain Segarra Adin Hrnjic help from Igor Korover

46

We are studying PMT performance at MIT.

0

100

200

300

400

500

600

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2

Tim

ere

solu

tion

[ps]

Energy deposit [MeV]

2 m bar, 5× 5 cm2 cross section

R7724-10R7724-100

R13435R13089

Each ps of resolution costs $0.225.

47

We have developed a detailed simulation of the

experiment.

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1.7

0 0.2 0.4 0.6 0.8 1

αs

x ′

1.2

1.3

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1.5

1.6

1.7

0 0.2 0.4 0.6 0.8 1

48

Analytic model for momentum resolution

δp/p ≈√

(pEcσt)2/2 + E4w2/12/(mnz)

0%

0.5%

1%

1.5%

2%

2.5%

250 300 350 400 450 500 550 600

150 ps PMTs

300 ps PMTs500 ps PMTs

Mom

entu

mre

solu

tion

Neutron momentum [MeV]

7 cm bars10 cm bars

49

Analytic model for momentum resolution

δp/p ≈√

(pEcσt)2/2 + E4w2/12/(mnz)

0%

0.5%

1%

1.5%

2%

2.5%

250 300 350 400 450 500 550 600

150 ps

300 ps

500 ps

Mom

entu

mre

solu

tion

Neutron momentum [MeV]

7 cm bars10 cm bars

50

Background will be higher at large x ′.

0

2000

4000

6000

8000

10000

12000

14000

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Q2 > 2 GeV2W ′ > 1.8 GeVSignal

Random Bkg.

Cou

nts

x ′

51

Even with background, we expect

good statistical precision.

0

2000

4000

6000

8000

10000

12000

1.3 1.35 1.4 1.45 1.5 1.55

Counts

αs

0.25 < x ′ < 0.35

1.2%

1.5%

2.1%

2.8%4.2%

0

2000

4000

6000

8000

10000

12000

1.3 1.35 1.4 1.45 1.5 1.55

52

Even with background, we expect

good statistical precision.

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1.3 1.35 1.4 1.45 1.5 1.55

Counts

αs

x ′ > 0.5

3.3%

4.4%

6.1%8.2%

11%

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1.3 1.35 1.4 1.45 1.5 1.55

53

Expected Impact

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1 1.1 1.2 1.3 1.4 1.5 1.6

PLC suppression

Rescaling

Binding

LAD

BANDBou

ndF2

/Fr

eeF2

αs

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1 1.1 1.2 1.3 1.4 1.5 1.6

54

As the mechanical design is getting fixed

we are moving to a full Geant4 sim.

Efrain Segarra

Erez Cohen

55

The important points

1 Recoil tagging can test the

EMC-SRC connection.

2 LAD will detect recoil protons

in Hall C

3 BAND will detect recoil

neutrons in Hall B

ee'

recoilingspectator

56

The important points

1 Recoil tagging can test the

EMC-SRC connection.

2 LAD will detect recoil protons

in Hall C

3 BAND will detect recoil

neutrons in Hall B

scatteredelectron

jet from struck quark

Deuterium

LAD

11 GeV e–

SHMS

HMS

GEMsspectatorproton

JLab Hall C

57

The important points

1 Recoil tagging can test the

EMC-SRC connection.

2 LAD will detect recoil protons

in Hall C

3 BAND will detect recoil

neutrons in Hall B

scatteredelectron

jet from struck quark

Deuterium

Spectatorneutron

BAND

11 GeV e–

CLAS12

JLab Hall B

58

The important points

We will make a definitive statement about the role of virtuality in the

EMC effect.

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1 1.1 1.2 1.3 1.4 1.5 1.6

PLC suppression

Rescaling

Binding

LAD

BANDBou

ndF2

/Fr

eeF2

αs

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1 1.1 1.2 1.3 1.4 1.5 1.6

59

The EMC effect is still a puzzle.

BAND and LAD will tell us if we are

putting the pieces in the right spot.

−0.1

0

0.1

0.2

0.3

0.4

0.5

01

23

45

6

2 H

3 He

4 He

9 Be

12 C

56 Fe

197 Au

EMCSlope(−dR/dxB)

SRC-pair d

ensity(a2)

60