1. Large Acceptance Detector (LAD) for 12 GeV Hall C
Exclusive measurements of Short Range Correlations and more
Physics opportunities in Hall C at 12 GeV
Hall C Meeting,
Monday, August 4, 2008
Jefferson Lab, Newport News, VA USA
Eli Piasetzky
Tel Aviv University, ISRAEL

2. Large Acceptance Detector (LAD)
Large solid angle multi particle (charged and neutral) detector
HMS e’
SHMS
p,π,… e
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 cm-2 sec-1 ( times the planned luminosity for CLAS).

3. The physics driving the LAD detector
Short Range Correlations (SRC)
EMC
Hadronization
Study of GPDs
Nuclear Matter in non - equilibrium condition

4. Results (summary) 12C 12C 2N –SRC dominance np-SRC dominance ~18 %
18±5%
1±0.3%
2N –SRC dominance
np-SRC dominance ~18 %
The uncertainties allow a few percent of:
more than 2N correlations
Non - nucleonic degrees of freedom
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]

5. 1N >> 2N - SRC >> 3N – SRC.
0.6±0.2%
19±4% 3N
cure
XB>2
PR / PAC 33 or

6. Exclusive measurement:
From (e,e’p) + N to (e,e’p)+2N
From
triple coincidence (2N SRC) to
4 fold coincidence (3N SRC)
star geometry
Need to detect two recoil nucleons
~800 MeV/c
Needs large acceptance multi particle detector
Colinear geometry :
~400 MeV/c
0.3-1 GeV/c p and n

7. For a 1 fm separation, the central density is about 4 times the nuclear central density
Nucleons
2N-SRC
  4o
~1 fm
Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?

8. Looking for non-nucleonic degrees of freedom
2N-SRC
1.f
~1 fm
Breaking the pair will yield more backward Δ, π , k
Nucleons
The signature of a non-nucleonic SRC intermediate state is a large branching ratio to a non-nucleonic final state.

9. Expected Δ’s rates 5-10% of recoil N
Looking for non-nucleonic degrees of freedom
Expected Δ’s rates 5-10% of recoil N
Detected by spectrometer
4 fold coincidence
2 particles in the backward detector
3-5 fold coincidence
2-4 particles in the backward detector

10. Expected Δ’s rates 5-10% of recoil N
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

11. Kinematics
pΔ=640 MeV/c
With SHMS(e) and HMS(p) acceptances
and Γ=110 MeV Δ
Needs large acceptance multi particle detector

12. Even the triple coincidence SRC experiment could be done better with a larger acceptance detector.
Measured ratio
Extrapolation factor ~10
The limited acceptance allows determination of only two components of the pair c.m. momentum with very limited acceptance.
Extrapolated ratio
R.B. Wiringa, R. Schiavilla, Steven C. Pieper, J. Carlson . Jun arXiv:  [nucl-th]

13. EMC A large acceptance detector allows tagging of the DIS event
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

14. 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

15. GPDs Hall B Hall C With a large acceptance detector:
With a deuteron one can measure simultaneously both protons and neutrons by detecting the recoil neutron or proton, respectively ?
low mass πN system- a test of chiral symmetry

16. 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?

17. Large Acceptance Detector
Multi particle detection
Particle ID
Large solid angle- 4π – non-symmetric opening in the forward hemisphere
Cover up to ~1800 p e e’ Δ
Large (full) luminosity
Can operate in coincidence with small solid angle, high resolution spectrometer / spectrometers

18. TOF P Phase space coverage CLAS Large –angle TOF scintillators
120
TOF Counters
Target Chamber
TOF Counters

19. Add two sectors at beam high
Phase space coverage
Beam View
Beam in
Add two sectors at beam high

20. Beam Left View
Sector #1
Sector #3
Sector 1:
Sector 2:
Sector 3:
Polar angle acceptance
Sector #2

21. Beam Right View
Sector #4
Sector #6
Polar angle acceptance
Sector 4:
Sector 5:
Sector 6:
Sector #5

22. Sector #4
Sector #6
Sector #1
n-detectors
Sector #3
1420
n-detectors
1720
Sectors 2 and 5 are not shown

23. neutron detection 5 PID 10 cm 5cm 22 X (370-450) X 5.08 cm3
~140 counters
With ~ 80 counters / layer we can cover the beam height ±80 cm behind sectors 3 and 6.
10x(10-25)x( ) cm3

24. PID p d
beam π
~140 counters
TOF
22 X X 5.08 cm3
PID can be better done by a partial acceptance (sectors 3 and 6) where more than one counter is on the line of sight.
at about 4 m from the target

25. Luminosity: singles rates
cm-2 sec > kHz/m2
(The large counters are ~ 1m2 )
cm-2 sec > MHz
(the planned luminosity for 12GeV CLAS is 1035)
(The Hall A E luminosity was 5·1037 )

26. (e, e’ppp) ~ 0.2 ·1% ·0.1 → ~1 events / hr
Luminosity: rates
Rate of (e,e’p) with Pmiss= MeV/c, Hall A experiment E01-015: 0.2 Hz
cm-2 sec-1 / cm-2 sec-1 = 1 / 10
LAD:
(e, e’ppp) ~ 0.2 ·1% ·0.1 → ~1 events / hr
(e,e’p) rate
~100 events / week
(e,e’ppp)/(e,e’p)
Luminosities ratio
(higher rates taking into account the spectrometers solid angles)

27. Luminosity: Signal/BG
Pmis=“300” MeV/c
(Signal : BG= 1.5:1)
Pmis=“400” MeV/c
(Signal : BG= 2.3:1)
TOF corrected by the momentum determination based on Eloss
Pmis=“500” MeV/c
(Signal : BG= 4:1)
Δt~15 nsec
Hall A experiment E01-015

28. Luminosity: number of pairs
Average number of hits per event:
2MHz ·15 nsec = 3% %·140 = 4 hits/event (6 pairs/event)
For each pair of identified protons with momentum within physically possible range calculate:
Only pairs with
are relevant
BigBite is ~100msr, assuming 1Sr / 2π i.e <1 pair on average

29. Luminosity: Signal/BG
(e, e’pp)/(e,e’p) Hall A experiment E01-015:
(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.)
(calculation for a single counter:)
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 MeV/c (the spectrometer based trigger) .

30. 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 (the planned 12 GeV CLAS covers up to 1350 )
Possible trigger by two high resolution spectometers

31. Quo vadis ? 2008 Conceptual detector design
Simulations
A physics proposals on SRC to the next PAC
Other proposals ?

32. Acknowledgment Discussions and ideas exchange with: Stepan Stepanyan
Sebastian Kuhn
Larry Weinstein
Steve Wood
Rolf Ent
Preliminary design
Mike Fowler
Dave Kashy
Paul Brindza

33. SRC in nuclei Roadmap SRC in nuclei
What is the role played by short range correlation of more than two nucleons ?
How to relate what we learned about SRC in nuclei to the dynamics of neutron star formation and structure ?
  5o
2N-SRC
SRC
in nuclei
1.f
~1 fm
1.7 fm
1.7f
o = 0.16 GeV/fm3
Nucleons
Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?
NN interaction: what is the role played by the repulsive core ?

34. n-detection efficiency ~20% +15%(?)
PID d p
n-detection efficiency ~20% +15%(?) π
TOF
Also E vs. ΔE
5 cm
beam
20 cm
beam
LAC
LAC
~200 counters

35. Quo vadis ? 2008 2-3 physics proposals to the 12 GeV PAC
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

36. Large Angle Calorimeter (LAC)
2 mm lead foil
1.5 cm plastic Scintillator
33 layers
neutron momentum [GeV/c]

37. The CLAS as a 4π-forward detector
For the new 12 GeV clas:
The current magnet, Drift chambers, and scintillator counters are not to be used.
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.
Improve n-detection

38. The CLAS as a 4π-forward detector
TOF
CER
CAL
DC1
DC2
DC3

39. CLAS 3-D View

40. SRC in nuclei Roadmap SRC in nuclei
What is the role played by short range correlation of more than two nucleons ?
How to relate what we learned about SRC in nuclei to the dynamics of neutron star formation and structure ?
  5o
2N-SRC
SRC
in nuclei
1.f
~1 fm
1.7 fm
1.7f
o = 0.16 GeV/fm3
Nucleons
Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?
NN interaction: what is the role played by the repulsive core ?

41. 12C: 20±4.5 % 18±4.5 % 0.95 ± 0.2 % 0.95 ± 0.2 % 80±4.5% 2N-SRC np-SRC
pp-SRC
0.95 ± 0.2 %
nn-SRC
A single “particle” in an average potential
0.95 ± 0.2 %
80±4.5%
The uncertainties allow a few percent of:
more than 2N correlations
Non nucleonic degrees of freedom

42. Identifying Future Experiments
Looking for SRC with more than 2 nucleons:

43. Identifying Future Experiments
Looking for SRC with more than 2 nucleons:
The problems:
The cross sections are small.
1N >> 2N - SRC >> 3N – SRC.
Questions
What is the signature for 3N correlation ?
star geometry :
What is the difference from two 2N correlations ?
What is the expected isospin structure of the 3N ?

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

45. Identifying Future Experiments
Looking for SRC with more than 2 nucleons:
Colinear geometry :
Initial configurations
~800 MeV/c
A very strong isospin dependence is expected for the 2N part. For the 3N?
~400 MeV/c
The 2N-SRC interaction is suppressed, opening a window of opportunity to identify 3N correlation.
The signal of today is tomorrow’s background

46. FSI are strong function of θ
Identifying Future Experiments
Looking for SRC with more than 2 nucleons:
Colinear geometry
~800 MeV/c
FSI are strong function of θ
SRC are not

47. Identifying Future Experiments
Looking for non-nucleonic degrees of freedom
1.f
Nucleons
2N-SRC
  5o
~1 fm
Breaking the pair will yield more backward Δ, π , k
The signature of a non-nucleonic SRC intermediate state is a large branching ratio to a non nucleonic final state.

48. p, n, π-, π+ k - triple coincidence
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

49. Identifying Future Experiments
Looking for non-nucleonic degrees of freedom
“np”  pn
pΔ0 p π - p
“pp”  pp
pΔ+ p π+ n
4 fold coincidence
Expected rates 5-10% of recoil N

50. Kinematics Δ

51. The selected kinematics for E01-015p
Pm = “300”,”400”,”500” MeV/c
Ee’ = GeV e’
Ee = GeV
19.50 e
50.40
40.1, 35.8, 32.00
P = MeV/c
n or p
p = 1.45,1.42,1.36 GeV/c
Q2=2 (GeV/c)2 p
qv=1.65 GeV/c
99 ± 50
Increasing, energy, ω,NΔ ?
X=1.245

52. The selected kinematics
Increasing, energy and ω, NΔ p
Ee’ = 9.8 GeV
Pmiss =770 MeV/c e’
Ee = 11 GeV
8.80 e
48.50
34 0
PΔ =770 MeV/c
Cannot produce backward going Δ.
Cannot produce larger momentum difference between the recoil Δ and the struck nucleon. p e e’ Δ
p = 1.32 GeV/c
Pmiss =1.32 GeV/c
PΔ =770 MeV/c
p = 1.32 GeV/c Δ
Q2=2.5 (GeV/c)2 p
qv=1.65 GeV/c
X=1.12

53. Ee= 11. 00000 Eout= 9. 790000 theta_e = 8. 800000 Q2= 2. 535372 x= 1
Ee= Eout= theta_e = Q2= x= input angle of (qe) and (qp) planes E+00 theta of q: 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 missing E+00 recoil tet between recoil and scattred proton pmiss in the q direction
Ee= Eout= theta_e = Q2= x= input angle of (qe) and (qp) planes E+00 theta of q: 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 missing E+00 recoil tet between recoil and scattred proton pmiss in the q direction

54. The selected kinematics for the measurement
Pm = “640 MeV/c
Ee’ = 9 GeV p e’
Ee = 11 GeV
8.20 e
16.60
31.50
PΔ= “640 MeV/c p
p = 2.3 GeV/c
Ee= Eout= theta_e = Q2= x= input angle of (qe) and (qp) planes E+00 theta of q: 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 missing E+00 recoil tet between recoil and scattred proton pmiss in the q direction Δ
Q2=2 (GeV/c)2
1000
qv=2.5 GeV/c
X=0.5

55. With SHMS(e) and HMS(p) acceptances
pΔ=640 MeV/c
With SHMS(e) and HMS(p) acceptances
and Γ=110 MeV
Needs large acceptance multi particle detector

56. The LargeAcceptanceMINUSFORWARD detector
Multi particle detection
Particle ID
Large solid angle- 4π – non symmetric gape at the forward hemisphere p e e’ Δ
Large (full) luminosity
Can operate in coincidence with small solid angle high resolution spectrometer / spectrometers

58. CLAS12 Toroidal field  < 45o Solenoidal field 45 <  < 135o
TOF DC
CO2 Cer
Solenoid
Toroid
CF4 Cerenkov
Calorimeter

59. SRC in nuclei Roadmap SRC in nuclei
What is the role played by short range correlation of more than two nucleons ?
  5o
2N-SRC
SRC
in nuclei
1.f
~1 fm
1.7 fm
1.7f
o = 0.16 GeV/fm3
Nucleons
Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?

60. 12C: 20±4.5 % 18±4.5 % 0.95 ± 0.2 % 0.95 ± 0.2 % 80±4.5% 2N-SRC np-SRC
pp-SRC
0.95 ± 0.2 %
nn-SRC
A single “particle” in an average potential
0.95 ± 0.2 %
80±4.5%
The uncertainties allow a few percent of:
more than 2N correlations
Non nucleonic degrees of freedom

63. TOF scintillators
LAC

64. Singles rates (The large counters are ~ 1m2 )
cm-2 sec > kHz/m2
(The large counters are ~ 1m2 )
cm-2 sec > MHz

65. 12C
12C ? ?
PRELIMINARY
12C
12C

66. Proposal : same luminosity as before
i.E : 30 microA on mm 12C at 20 deg
Can the chambers at 100 deg hold such luminosity?

71. Sector #1
Sector #4
Sector #6
Sector #3
Sector #5
Sector #2