Large Acceptance Detector (LAD) for 12 GeV Hall C

Eli Piasetzky

Tel Aviv University, ISRAEL

Hall C Meeting, Monday, August 4, 2008 Jefferson Lab, Newport News, VA USA

Physics opportunities in Hall C at 12 GeV

Exclusive measurements of Short Range Correlations and more

e

e’

p,π,…

*

Large solid angle multi particle (charged and neutral) detector

HMS

SHMS

Coverage of a large fraction of the hemisphere (“backward” =4π-forward) consistent with the forward spectrometers.

Ability to detect multi-charge particles with good PID and moderate momentum resolution.

Ability to detect neutrons with high efficiency.

Ability to operate at a luminosity of 1036-1038 cm-2 sec-1 (10-1000 times the planned luminosity for CLAS).

Large Acceptance Detector (LAD)

The physics driving the LAD detector

Short Range Correlations (SRC)

EMC

Hadronization

Study of GPDs

Nuclear Matter in non - equilibrium condition

np-SRC dominance ~18 %

12C

Results (summary)

The uncertainties allow a few percent of:

more than 2N correlations

Non - nucleonic degrees of freedom

2N –SRC dominance

18±5%

1±0.3%

12C

Sensitivity required fo the next generation of SRC measurements 0.1 – 1 % of (e, e’ p).[(0.5-5)% of (e,e’p) with Pmiss>300 MeV/c]

19±4%0.6±0.2%

2N

3N

PR 08-14 / PAC 33

1N >> 2N - SRC >> 3N – SRC.

cure

XB>2

or

~800 MeV/c~800 MeV/c

~400 MeV/c~400 MeV/c

star geometry

Colinear geometry :

From (e,e’p) + N to (e,e’p)+2N

Exclusive measurement:

From

triple coincidence (2N SRC)

to

4 fold coincidence (3N SRC)

Needs large acceptance multi particle detector

Need to detect two recoil nucleons

0.3-1 GeV/c p and n

•Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?

For a 1 fm separation, the central density is about 4 times the nuclear central density

1.f

Nucleons

2N-SRC 4o

~1 fm

Looking for non-nucleonic degrees of freedom

The signature of a non-nucleonic SRC intermediate state is a large branching ratio to a non-nucleonic final state.

... cba NNNSRC

1c,...b, ,0 a

Breaking the pair will yield more backward Δ, π , k

1.f

Nucleons

2N-SRC 5o

~1 fm

Looking for non-nucleonic degrees of freedom

Expected Δ’s rates 5-10% of recoil N

pnp

nnnn

)(

""

4 fold coincidence

NNN"" ""NN

))((

""00 pp

nnnn

) )((

""0 np

npnp

2 particles in the backward detector

))((or

))((

""0

pp

pp

pppp

ppp

npnp

)(

""0

pnp

pppp

)(

""

3-5 fold coincidence

2-4 particles in the backward detector

Detected by spectrometer

Title:Search for cumulative Delta 0(1232) and

Delta + + (1232) isobars in neutrino interactions with neon nuclei

Authors: Ammosov, V. V.; Asratyan, A. É.; Burtovoǐ, V. S.; Gapienko, V. A.; Gapienko, G. S.; Gorichev, P. A.; Denisov, A. G.; Zaets, V. G.; Klyukhin, V. I.; Koreshev, V. I.; Kruchinin, S. P.; Kubantsev, M. A.; Makhlyueva, I. V.; Pitukhin, P. V.; Sirotenko, V. I.; Slobodyuk, E. A.; Usubov, Z. U.; Fedotov, A. V.; Shevchenko, V. G.; Shekelyan, V. I.

Publication:

Journal of Experimental and Theoretical Physics Letters, Vol. 40, p.1041

Publication Date:

09/1984

Expected Δ’s rates 5-10% of recoil N

Δ

Kinematics

pede22 =)( mppq fd

pΔ=640 MeV/c

With SHMS(e) and HMS(p) acceptancesand Γ=110 MeV

Needs large acceptance multi particle detector

Extrapolation factor ~10

)',()/',( 1212 peeCppeeC

Measured ratio

Extrapolated ratio

The limited acceptance allows determination of only two components of the pair c.m. momentum with very limited acceptance.

Even the triple coincidence SRC experiment could be done better with a larger acceptance detector.

R.B. Wiringa, R. Schiavilla, Steven C. Pieper, J. Carlson . Jun 2008. arXiv:0806.1718 [nucl-th]

A large acceptance detector allows tagging of the DIS event

EMC

High nuclear density tagging :

A recoil high momentum nucleon to the backward hemisphere is a signature of 2N-SRC i.e large local nuclear density.

Due to the dominance of np-SRC pairs: a recoil neutron tags the proton structure function a recoil proton tags the neutron structure function

Flavor tagging :

Identifying a π + or π - with a large z can point to the flavor of the struck quark ( u or d).

Recoil and forward tagging allows the study of u, d in p, n

Hadronization

Measure the multiplicity and the type of emitted particles in a large acceptance “backward direction ” in coincidence with the forward (large z) leading π +, π -, k +, k - particle.

Difference in hadronization of different quarks

Difference between hadronization in free space and the nuclear medium

GPDs

NN *

Hall C np *

With a large acceptance detector:

NL*

)(* NNL low mass πN system- a test of chiral symmetry

)(* KNL

With a deuteron one can measure simultaneously both protons and neutrons by detecting the recoil neutron or proton, respectively ?

Hall B

Nuclear Matter in non - equilibrium condition

Using hard processes to remove a single or a few nucleons from the nucleus creates a non-stable state.

How does such a non-stable state decay to a stable system?

Large solid angle- 4π – non-symmetric opening in the forward hemisphere

Large (full) luminosity

Can operate in coincidence with small solid angle, high resolution spectrometer / spectrometers

Multi particle detection

Particle ID

pe

e’

*

Δp

Large Acceptance Detector

Cover up to ~1800

P

SHMS @5.50HMS @ 120

TOF CountersTarget Chamber

TOF Counters

Phase space coverage

TOF

CLAS Large –angle TOF scintillators

Beam in

Beam View

Add two sectors at beam high

Phase space coverage

Beam Left View

Sector #1

Sector #2

Sector #3

Sector 1: 82-1420

Sector 2: 97-1290

Sector 3: 117-1720

Polar angle acceptance

Beam Right View

Sector #4

Sector #5

Sector #6

Polar angle acceptanceSector 4: 75-1420

Sector 5: 97-1060

Sector 6: 77-1030

1420

1720n-detectors

n-de

tect

ors

Sector #1

Sector #3

Sector #4 Sector #6

Sectors 2 and 5 are not shown

5

PID

22 X (370-450) X 5.08 cm3

10x(10-25)x(100-160) cm3

~140 counters

With ~ 80 counters / layer we can cover the beam height ±80 cm behind sectors 3 and 6.

neutron detection

5cm

10 cm

π

p

d

~140 counters

beam

TOF

PID

22 X 370-450 X 5.08 cm3

at about 4 m from the target

PID can be better done by a partial acceptance (sectors 3 and 6) where more than one counter is on the line of sight.

Luminosity: singles rates

3 1033 cm-2 sec-1 ----> 1 kHz/m2 (The large counters are ~ 1m2 )

6 1036 cm-2 sec-1 ----> 2 MHz

(the planned luminosity for 12GeV CLAS is 1035)

(The Hall A E01-015 luminosity was 5·1037 )

Luminosity: rates

6 1036 cm-2 sec-1 / 5 1037 cm-2 sec-1 = 1 / 10

Rate of (e,e’p) with Pmiss=300-600 MeV/c, Hall A experiment E01-015: 0.2 Hz

LAD: (e, e’ppp) ~ 0.2 ·1% ·0.1 → ~1 events / hr

~100 events / week(e,e’p) rate

(e,e’ppp)/(e,e’p)

Luminosities ratio

(higher rates taking into account the spectrometers solid angles)

Luminosity: Signal/BG

TOF corrected by the momentum determination based on Eloss

Pmis=“300” MeV/c

Pmis=“400” MeV/c

Pmis=“500” MeV/c

(Signal : BG= 1.5:1)

(Signal : BG= 2.3:1)

(Signal : BG= 4:1)

Δt~15 nsecHall A experiment E01-015

12 37 sec10 5.1 cmLN

For each pair of identified protons with momentum within physically possible range calculate:

21 ppprecoil

Only pairs with missp-

recoilp

Luminosity: number of pairs

Average number of hits per event:

2MHz ·15 nsec = 3% 3%·140 = 4 hits/event (6 pairs/event)

are relevant

BigBite is ~100msr, assuming 1Sr / 2π i.e <1 pair on average

Luminosity: Signal/BG

(e, e’pp)/(e,e’p) Hall A experiment E01-015:

5.1155

%10

sin,

,

nsMHtRR

fR

BG

signal

Zglesepe

epe

(e, e’ppp)/(e,e’p) in LAD Hall C:

(assuming the worst case: that an individual recoil proton does not have any directional correlation with Pmiss.)

'8)152(

140'

)(

'

22sin,

,f

nsMH

f

tRRN

fR

BG

signal

Zglesepe

epe

To be sensitive to 1% of the (e, e’p) we need to be sensitive to about 5% of the (e,e’p) with Pmiss between 300 -600 MeV/c (the spectrometer based trigger) .

4.0'8 fBG

signal

(calculation for a single counter:)

What can be done with LAD that cannot be done with the planned 12 GeV CLAS ?

Up to ~100x the planned luminosity for the 12 GeV CLAS (1035).

Backward coverage up to 1720 (the planned 12 GeV CLAS covers up to 1350 )

Possible trigger by two high resolution spectometers

A physics proposals on SRC to the next PAC

Conceptual detector design

2008

Simulations

Other proposals ?

Acknowledgment

Stepan Stepanyan

Sebastian Kuhn

Steve Wood

Rolf Ent

Discussions and ideas exchange with:

Larry Weinstein

Preliminary design

Mike Fowler

Dave Kashy

Paul Brindza

How to relate what we learned about SRC in nuclei to the dynamics of neutron star formation and structure ?

SRC

in nuclei

NN interaction: what is the role played by the repulsive core ?

•Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?

What is the role played by short range correlation of more than two nucleons ?

SRC in nuclei

Roadmap

1.f

Nucleons

2N-SRC

1.7f

o = 0.16 GeV/fm3

5o

~1 fm 1.7 fm

π

pd

beam

beam

~200 counters

20 cm

5 cmAlso E vs. ΔE

PID

TOF

ΔE

n-detection efficiency ~20% +15%(?)

LACLAC

Short Range Correlations (SRC)

EMC

Hadronization

Study of GPDs

Nuclear Matter in non - equilibrium condition

2-3 physics proposals to the 12 GeV PAC

Conceptual detector design

2008

Large Angle Calorimeter (LAC)

2 mm lead foil

1.5 cm plastic Scintillator

33 layers

neutron momentum [GeV/c]

Improve n-detection

For the new 12 GeV clas:

The current magnet, Drift chambers, and scintillator counters are not to be used.

The CLAS as a 4π-forward detector

Need new power supplies, and electronics

Require a careful, non trivial dismount of the current detector at Hall B and non trivial setup at hall c.

The CLAS as a 4π-forward detector

TOF CER CAL

DC1DC2DC3

CLAS 3-D View

How to relate what we learned about SRC in nuclei to the dynamics of neutron star formation and structure ?

SRC

in nuclei

NN interaction: what is the role played by the repulsive core ?

•Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?

What is the role played by short range correlation of more than two nucleons ?

SRC in nuclei

Roadmap

1.f

Nucleons

2N-SRC

1.7f

o = 0.16 GeV/fm3

5o

~1 fm 1.7 fm

12C:

18±4.5 %

0.95 ± 0.2 %

0.95 ± 0.2 %

2N-SRCnp-SRC

pp-SRC

nn-SRC

20±4.5 %

80±4.5%

The uncertainties allow a few percent of:

more than 2N correlations

Non nucleonic degrees of freedom

A single “particle” in an average potential

Identifying Future Experiments

Looking for SRC with more than 2 nucleons:

Identifying Future Experiments

Looking for SRC with more than 2 nucleons:

The problems:

The cross sections are small.

1N >> 2N - SRC >> 3N – SRC.

star geometry :What is the signature for 3N correlation ?

Questions

What is the difference from two 2N correlations ?

What is the expected isospin structure of the 3N ?

Identifying Future Experiments

Looking for SRC with more than 2 nucleons:

The problems:

The cross sections are small.

1N >> 2N - SRC >> 3N – SRC.

The cure for 1N background is : large pmiss and/or large XB

The cure for 2N-SRC:

XB>2 or

suppression of the 2N-SRC at prel=300-600 MeV/c for nn or pp pairs.

Identifying Future Experiments

Looking for SRC with more than 2 nucleons:

Colinear geometry :

Initial configurations

~800 MeV/c~800 MeV/c

The signal of today is tomorrow’s background

The 2N-SRC interaction is suppressed, opening a window of opportunity to identify 3N correlation.

~400 MeV/c~400 MeV/c

A very strong isospin dependence is expected for the 2N part. For the 3N?

Identifying Future Experiments

Looking for SRC with more than 2 nucleons:

Colinear geometry

~800 MeV/c~800 MeV/c

FSI are strong function of θ

SRC are not

Identifying Future Experiments

Looking for non-nucleonic degrees of freedom

The signature of a non-nucleonic SRC intermediate state is a large branching ratio to a non nucleonic final state.

... cba NNNSRC

1c,...b, ,0 a

Breaking the pair will yield more backward Δ, π , k

1.f

Nucleons

2N-SRC 5o

~1 fm

Looking for non-nucleonic degrees of freedom

In coincidence with (e, e’p), as a function of the missing momentum we want to detect;

p, n, π-, π+ k - triple coincidence

Identifying Future Experiments

Looking for non-nucleonic degrees of freedom

pΔ0 p π - p

“np” pn

“pp” pp

pΔ+ p π+ n

p 0

n 4 fold coincidence

Expected rates 5-10% of recoil N

Δ

Kinematics

pede22 =)( mppq fd

p

e

e’

*n or p

p

Pm =

“30

0”,”

400”

,”50

0” M

eV/c

99 ±50

P =

300

-600

MeV

/c

Ee = 4.627 GeV

Ee’ = 3.724 GeV

Q2=2 (GeV/c)2

qv=1.65 GeV/c

50.40

19.50

40.1 ,35.8 ,32.00

p = 1.45,1.42,1.36 GeV/c

The selected kinematics for E01-015

X=1.245Increasing, energy, ω,NΔ ?

p

e

e’

*Δ

p

Ee = 11 GeV

Ee’ = 9.8 GeV

Q2=2.5 (GeV/c)2

qv=1.65 GeV/c

48.50

8.80

34 0

p = 1.32 GeV/c

The selected kinematics

X=1.12

Increasing, energy and ω, NΔ

Pmiss =770 MeV/c

PΔ =770 MeV/c

Cannot produce backward going Δ.

Cannot produce larger momentum difference between the recoil Δ and the struck nucleon.p

ee’

*

Δ p

p = 1.32 GeV/c

Pmiss =1.32 GeV/c

PΔ =770 MeV/c

Ee= 11.00000 Eout= 9.960000 theta_e = 8.200000 Q2= 2.240232 x= 1.147892

input angle of (qe) and (qp) planes 0.0000000E+00 theta of q: -51.20859

The format of the following output is:

type of the particle, momentum, angle vs q, angle vs e, azimuthal angle in lab

knock-out nucleon 1.200000 5.490372 45.71821 180.0000 missing 0.6385024 169.6408 118.4322 0.0000000E+00

recoil 0.6385024 10.35917 61.56776 180.0000 tet between recoil and scattred proton -15.84955

pmiss in the q direction 0.6280947

Ee= 11.00000 Eout= 9.790000 theta_e = 8.800000 Q2= 2.535372 x= 1.116600 input angle of (qe) and (qp) planes 0.0000000E+00 theta of q: -48.49650 The format of the following output is: type of the particle, momentum, angle vs q, angle vs e, azimuthal angle in lab knock-out nucleon 1.328000 13.52419 34.97231 180.0000 missing 0.7737520 156.3361 107.8397 0.0000000E+00 recoil 0.7737520 23.66388 72.16035 180.0000 tet between recoil and scattred proton -37.18803 pmiss in the q direction 0.7086919

p

e

e’

*Δ

pPm

= “

640

MeV

/c

1000

Ee = 11 GeV

Ee’ = 9 GeV

Q2=2 (GeV/c)2

qv=2.5 GeV/c

31.50

8.20

16.60

p = 2.3 GeV/c

The selected kinematics for the measurement

X=0.5

P Δ=

“640

MeV

/c

Ee= 11.00000 Eout= 9.000000 theta_e = 8.200000 Q2= 2.024307 x= 0.5393709 input angle of (qe) and (qp) planes 0.0000000E+00 theta of q: -31.53330 The format of the following output is: type of the particle, momentum, angle vs q, angle vs e, azimuthal angle in lab knock-out nucleon 2.300000 14.94191 16.59142 179.9802 missing 0.6368749 111.3839 79.85064 0.0000000E+00 recoil 0.6368749 68.61605 100.1494 180.0000 tet between recoil and scattred proton -83.55794 pmiss in the q direction 0.2322146

pΔ=640 MeV/c

With SHMS(e) and HMS(p) acceptancesand Γ=110 MeV

With SHMS(e) and HMS(p) acceptances

Needs large acceptance multi particle detector

Large solid angle- 4π – non symmetric gape at the forward hemisphere

Large (full) luminosity

Can operate in coincidence with small solid angle high resolution spectrometer / spectrometers

Multi particle detection

Particle ID

pe

e’

*

Δp

The LargeAcceptanceMINUSFORWARD detector

CLAS12

Solenoid

Toro

id

Cal

orim

eter

CF 4

Cer

enko

v

Toroidal field < 45o

Solenoidal field 45 < < 135o

DC TOF

CO2 Cer

SRC

in nuclei

•Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?

What is the role played by short range correlation of more than two nucleons ?

SRC in nuclei

Roadmap

1.f

Nucleons

2N-SRC

1.7f

o = 0.16 GeV/fm3

5o

~1 fm 1.7 fm

12C:

18±4.5 %

0.95 ± 0.2 %

0.95 ± 0.2 %

2N-SRCnp-SRC

pp-SRC

nn-SRC

20±4.5 %

80±4.5%

The uncertainties allow a few percent of:

more than 2N correlations

Non nucleonic degrees of freedom

A single “particle” in an average potential

LAC

TOF scintillators

Singles rates

3 1033 cm-2 sec-1 ----> 1 kHz/m2 (The large counters are ~ 1m2 )

6 1036 cm-2 sec-1 ----> 2 MHz

PRELIMINARY

12C

12C12C

12C

?

?

Proposal : same luminosity as before

i.E : 30 microA on 0.25 mm 12C at 20 deg

12 37 sec10 5.1 cmLN

Can the chambers at 100 deg hold such luminosity?

Sector #2

Sector #1

Sector #3

Sector #4

Sector #5

Sector #6