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“Backward” Particle Detection for 12 GeV in Hall C

“Backward” Particle Detection for 12 GeV in Hall C. Hall C Meeting, January 18-19, 2008 Jefferson Lab, Newport News, VA USA. Eli Piasetzky. Tel Aviv University, ISRAEL. Large solid angle multi particle (charge and neutral) detector. HMS. SHMS. e’. p, π ,…. e.

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“Backward” Particle Detection for 12 GeV in Hall C

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  1. “Backward” Particle Detection for 12 GeV in Hall C Hall C Meeting, January 18-19, 2008 Jefferson Lab, Newport News, VA USA Eli Piasetzky Tel Aviv University, ISRAEL

  2. Large solid angle multi particle (charge and neutral) detector HMS SHMS e’ p,π,… e Coverage of a large fraction of the hemisphere (“backward” =4π-forward) consistent operation 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 10-100% of the full luminosity of Hall C (10-100 times the planned luminosity for CLAS).

  3. The physics driving a “4π-forward” detector Short Range Correlations (SRC) EMC Hadronization Study of GPDs Nuclear Matter in non - equilibrium condition

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

  5. 2N 1N >> 2N - SRC >> 3N – SRC. 0.6±0.2% 19±4% 3N cure XB>2 PR 08-14 / PAC 33 or

  6. ~800 MeV/c ~400 MeV/c Needs large acceptance multi particle detector ~800 MeV/c ~400 MeV/c 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 Colinear geometry : 0.3-1 GeV/c p and n

  7.  4o 2N-SRC 1.f ~1 fm Nucleons For a 1 fm separation, the central density is about 4 times nuclear central density • 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  5o 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. 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. Needs large acceptance multi particle detector Kinematics pΔ=640 MeV/c With SHMS(e) and HMS(p) acceptances and Γ=110 MeV Δ

  11. Even the triple coincidence SRC experiment could be done better with a larger acceptance detector. Measured ratio Extrapolated ratio The Limited acceptance allows determination of only two components of the pair cm momentum. Extrapolation factor ~10

  12. 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 a proton structure function a recoil proton tags a 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

  13. 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 hardonization in a free space and nuclear medium

  14. GPDs Hall B Hall C With a large acceptance detector: With Deuteron one can measure imultaneously both proton and neutron by detecting the recoil neutron or proton respectively ? low mass πN system- a test of chiral symmetry

  15. 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?

  16. p e’ e p Δ A (4π – forward) DETECTOR Multi particle detection Particle ID Large solid angle- 4π – non-symmetric opening in the forward hemisphere Cover up to ~1800 (the planed 12GeV CLAS cover up to 1350 only) Large (full) luminosity Can operate in coincidence with small solid angle, high resolution spectrometer / spectrometers

  17. G0 BONUS TPC

  18. PID d p π beam beam ~200 counters

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

  20. Quo vadis ? Short Range Correlations (SRC) EMC Hadronization Study of GPDs Nuclear Matter in non - equilibrium condition 2008 2-3 physics proposals to the 12 GeV PAC Conceptual detector design

  21. Acknowledgment Discussions and ideas exchange with: Stepan Stepanyan Sebastian Kuhn Larry Weinstein Steve Wood Rolf Ent

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

  23. 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

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

  25. CLAS 3-D View

  26. G0

  27. BONUS TPC

  28. SRC in nuclei Roadmap 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 Nucleons o = 0.16 GeV/fm3 • 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 ?

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

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

  31. 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 ?

  32. 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.

  33. ~800 MeV/c ~400 MeV/c ~800 MeV/c ~400 MeV/c Identifying Future Experiments Looking for SRC with more than 2 nucleons: Colinear geometry : Initial configurations A very strong isospin dependence is expected for the 2N part. For the 3N? The 2N-SRC interaction is suppressed, opening a window of opportunity to identify 3N correlation. The signal of today is tomorrow’s background

  34. ~800 MeV/c ~800 MeV/c Identifying Future Experiments Looking for SRC with more than 2 nucleons: Colinear geometry FSI are strong function of θ SRC are not

  35.  5o 2N-SRC 1.f ~1 fm Nucleons Identifying Future Experiments Looking for non-nucleonic degrees of freedom 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.

  36. 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

  37. 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

  38. Kinematics Δ

  39. The selected kinematics for E01-015 p Pm = “300”,”400”,”500” MeV/c Ee’ = 3.724 GeV e’ Ee = 4.627 GeV 19.50 e 50.40 40.1, 35.8, 32.00 P = 300-600 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

  40. p Pmiss =1.32 GeV/c e’ e p = 1.32 GeV/c PΔ =770 MeV/c Δ p 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 = 1.32 GeV/c Δ Q2=2.5 (GeV/c)2 p qv=1.65 GeV/c X=1.12

  41. 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 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

  42. 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 p PΔ= “640 MeV/c p = 2.3 GeV/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 Δ Q2=2 (GeV/c)2 1000 qv=2.5 GeV/c X=0.5

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

  44. p e’ e p Δ The LargeAcceptanceMINUSFORWARD detector Multi particle detection Particle ID 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

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

  46. SRC in nuclei Roadmap 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 Nucleons o = 0.16 GeV/fm3 • Are the nucleons in the SRC pair different from free nucleons (e.g size,shape, mass, etc.) ? Are they nucleons ?

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

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