Sept. 1, Few-Body 19 Bonn, Germany Few-body studies at HI  S Sean Stave Duke University & Triangle Universities Nuclear Laboratory (TUNL) And Mohammad Ahmed, Henry Weller Supported in-part by DOE grant DE-FG02-97ER

Sept. 1, Few-Body 19 Bonn, Germany Few-body experiments at HI  S Exploring A=2 and 3 Photodisintegration of the Deuteron & 3 He Importance Theoretical understanding of A=2,3 systems Global state of the experiments The role HIGS plays in the understanding of these systems What is on the horizon for HIGS

Sept. 1, Few-Body 19 Bonn, Germany Overview of A=2 The BBN Importance “Baryometer” The Deuteron Ideal Laboratory for the study of 2-body NP system Test of EFT and PM Calculations Target Beam Fundamental Sum Rules d d

Sept. 1, Few-Body 19 Bonn, Germany Understanding Few-Nucleon Systems 2 H, the simplest of Few-Body Systems The Theoretical Framework, A=2 Potential Model Effective Field Theory Sum Rules for Deuteron: Gerasimov-Drell-Hearn (GDH) & Forward Spin Polarizability (  0 )

Sept. 1, Few-Body 19 Bonn, Germany High precision NN-potentials, MEC, RC and  degrees of freedom Potential Model Calculations [H. Arenhovel, M. Schwamb et al.] The Pion-less Effective Field Theory Approach (EFT) [M. Savage, J-W. Chen & G. Rupak] E1 is computed up to N 4 LO and M1 is calculated up to N 2 LO, n-p radiative capture cross section predicted to an accuracy of 1% at CM energies ~ 1 MeV Most accurate theory describing 2-Nucleon system, Minimal data exist to test the predictions in this energy region The A=2 Theoretical Framework

Sept. 1, Few-Body 19 Bonn, Germany The Experimental Effort at HI  S Few-Body Studies at TUNL are carried out at HI  S Duke Free-Electron Laser Laboratory (HI  S)

Sept. 1, Few-Body 19 Bonn, Germany High Intensity Gamma-Ray Source: Booster Injector LINAC RF Cavity Mirror Optical Klystron FEL HI  S  -ray beam generation

Sept. 1, Few-Body 19 Bonn, Germany HI  S Parameters Circularly and Linearly Polarized nearly monoenergetic  -Rays from 2 to 60 MeV (90 MeV in the next 1 to 2 years) Total Gamma-Ray Flux ~ 10 8 to 10 9  /s

Sept. 1, Few-Body 19 Bonn, Germany All experiments were performed using linearly polarized beams Schreiber Tornow Sawatsky Blackston Sawatsky Blackston Ahmed Liquid Scintillating Detectors Liquid Scintillating Detectors in Blowfish Array Li-Glass Detectors in an Array  (135 ° ) E  = 3.58 MeV Eric Schrieber et al., 2000  (90 ° ) E  = 2.39 to 4.05 MeV Werner Tornow et al., 2003  ;  E  = 4 to 10 MeV Brad Sawatsky et al., 2005  (90 ° )E  = 2.44 to 4.0 MeV Mohammad Ahmed et al., 2007  ;  E  = 14 and 16 MeV Matthew Blackston et al., 2007  ;  total E  = 2.44 to 4.0 MeV Mohammad Ahmed et al., 2008 A=2 Experiments at HI  S

Sept. 1, Few-Body 19 Bonn, Germany Status of the “baryometer” Very little data in energy region for BBN

Sept. 1, Few-Body 19 Bonn, Germany d( ,n)p Cross section Expansion (M1) (E1) Polarized beam, unpolarized target Photon analyzing power measurement is proportional to the %E1 contribution to the total cross section

Sept. 1, Few-Body 19 Bonn, Germany Tornow et al. [PLB 574, 8 (2003)] 4-neutron detectors at a polar angle of 90 degrees and azimuthal angles of 0,90,180, and 270 degrees PRC 61, (2000) A=2 Results at HI  S Curves from EFT (Rupak et al.) Excellent agreement between data and PM and EFT

Sept. 1, Few-Body 19 Bonn, Germany No significant d-wave contributions are present at these low energies 4.0 MeV 3.5 MeV 2.44 MeV d( ,n)p at HI  S: Ahmed et al.

Sept. 1, Few-Body 19 Bonn, Germany Sum Rules for the Deuteron GDH : Arenhoevel et al. Spin-flip part of forward Compton scattering amplitude:

Sept. 1, Few-Body 19 Bonn, Germany GDH on the deuteron: Theory Arenhoevel et al. [NPA 631, 612c (1998)] Without relativistic corrections With relativistic corrections Negative at low energies Crosses zero at low energies

Sept. 1, Few-Body 19 Bonn, Germany Cross section difference expansion Polarized beam, polarized target If ignore d-waves and splitting of p-waves at low energies then ]

Sept. 1, Few-Body 19 Bonn, Germany A=2 Global Impact First-ever indirect determination of the GDH Sum Rule for Deuteron at low energies: -603 ± 43  b (Fit from thr. to 4 MeV, integrated from thr. to 6 MeV) Remember  =-3  (M1) Ahmed et al. [PRC 77, (2008)]

Sept. 1, Few-Body 19 Bonn, Germany A=2 GDH Comparison: Data and Theory Theory and Data integrated from threshold to 6 MeV Data: -603 ± 43  b Arenhoevel: -627  b -3  M1 :-662  b Experimentally confirmed negative value at low energy Ahmed et al. [PRC 77, (2008)]

Sept. 1, Few-Body 19 Bonn, Germany 88-cell Liquid Scintillating detector array 25% of 4  coverage  = 22.5 to degrees Blowfish A=2 Results at HI  S

Sept. 1, Few-Body 19 Bonn, Germany Blackston et al. [PRC 78, (2008)] d( ,n)p: Weller/Blackston’s Results 16 MeV Cross section and analyzing power at 16 MeV as a function of angle compared with Schwamb/Arenhoevel potential model High quality of data allowed a fit using 7 reduced transition matrix element amplitudes (phases fixed by np elastic scattering, SAID)

Sept. 1, Few-Body 19 Bonn, Germany First-ever observation of the splittings of the E1 (p-wave) amplitudes in low energy deuteron photo- disintegration [PRC 78, (2008)] d( ,n)p: Weller/Blackston’s Results 16 MeV Compared with Schwamb/Arenhoevel Potential Model Value if no p-wave splitting Note: d-wave results negligible and consistent with theory

Sept. 1, Few-Body 19 Bonn, Germany A=2 Global Impact First-ever observation of the p-wave splittings and confirmation of the relativistic corrections in the theory [PRC 78, (2008)]

Sept. 1, Few-Body 19 Bonn, Germany Sum Rules for the Deuteron Forward Spin-Polarizability: NLO, EFT calculation by X. Ji et al. Spin-flip part of forward Compton scattering amplitude:

Sept. 1, Few-Body 19 Bonn, Germany A=2  0 Comparison: Data and Theory First-ever indirect determination of  0 for deuteron at low energies Data integrated from threshold to 6 MeV Data: 3.75 ± 0.18 fm 4 Ji-LO:3.762 fm 4 Ji-NLO:4.262 fm 4 Arenhoevel:4.1 fm 4 Ahmed et al. [PRC 77, (2008)]

Sept. 1, Few-Body 19 Bonn, Germany 3 He, the simplest of Few-body Systems with 3NF and no excitation spectrum 3 He breakup Two-body Three-body System being considered What is our understanding of Few-Nucleon systems?

Sept. 1, Few-Body 19 Bonn, Germany Photodisintegration of 3 He between 7 and 20 MeV Total and differential Cross Section Total cross section for the 2-body breakup from 7 to 20 MeV, Tornow et al. Total and differential cross sections for the 3-body breakup, 12.8, 13.5, and 14.7 MeV, Perdue et al. The A=3 Experiments at HI  S

Sept. 1, Few-Body 19 Bonn, Germany The A=3 Theoretical Framework Recent efforts in understanding 3-body systems [Deltuva, Fonseca, Sauer] Coulomb Interaction in the 2- and 3-body photodisintegration channels CD-Bonn + , with  isobar mediating an effective 3NF and 2-, 3-nucleon currents, and still consistent with 2NF Still has issues at low-energies (3 Nucleon Analyzing Power Puzzle still stands!) The problem is also being worked upon by [Witala, Glockle, Nogga, and Golak, et al.]

Sept. 1, Few-Body 19 Bonn, Germany Current Status of the 3 He breakup cross section No measurement that is consistent across the energy range Clearly calls for a set of measurements with the same experimental conditions across the energy range 2-body 3-body total Shima & Nagai [PRC 73, (2006)] Compared with previous data and AV18 and AV18+Urbana IX Factor of 3 below theory

Sept. 1, Few-Body 19 Bonn, Germany Data are still under analysis for absolute normalization High Pressure 3 He/Xe cell A=3 at HI  S: 2-body breakup of 3 He, Tornow et al. Two-body peaks clearly separated

Sept. 1, Few-Body 19 Bonn, Germany 12.8, 13.5, and 14.7 MeV 3 He 3-body Breakup at HI  S: Weller, Perdue et al.

Sept. 1, Few-Body 19 Bonn, Germany 3 He 3-body Breakup: Theoretical Framework No coulomb interaction With coulomb interaction No sensitivity to coulomb interaction in the analyzing power Deltuva et al. [PRC 72, (2005)]

Sept. 1, Few-Body 19 Bonn, Germany Weller, Perdue et al. Initial Results From an APS talk by B. Perdue Phase-Space (PS) to PS + NP transition near 12.8 MeV About 25% below theory - HI  S Data - Deltuva - 3-body phase space

Sept. 1, Few-Body 19 Bonn, Germany Summary What have we accomplished? Confirmation of PM/EFT for the deuteron near BBN region First determination of the splitting of the p-waves in the photodisintegration of the deuteron First confirmation of GDH sum rule for the deuteron Confirmed large negative strength Confirmed positive going above 8 MeV and that it arises from the splitting of the p-waves First determination of the  0 sum rule for deuteron Precision 3-body photodisintegration cross section for 3He disagree with state-of-the-art theory at low energies

Sept. 1, Few-Body 19 Bonn, Germany New era of precision measurements at HI  S - PAC-09 has approved the following experiments for the next two years: Continue to measure deuteron photodisintegration cross section at lower energies (below 2.4 MeV) (Using OTPC) Direct measurements of the GDH on deuteron Compton scattering on the deuteron Measurement of two- and three-body cross sections of  + 3 He GDH Sum rule for 3 He Cross section measurement of  + 4 He Future plans at HI  S

Sept. 1, Few-Body 19 Bonn, Germany Calvin Howell et al. Werner Tornow et al. Henry Weller et al. Ying Wu et al. Acknowledgments Thank you!

Sept. 1, Few-Body 19 Bonn, Germany Additional slides

Sept. 1, Few-Body 19 Bonn, Germany Weller, Perdue et al. Initial Results Results from Gorbunov (1976) coarsely binned but consistent with current results A. N. Gorbunov, Proc. Of the P.N. Lebedev Phys. Inst., p. 1 (1976) 8-12 MeV MeV

Sept. 1, Few-Body 19 Bonn, Germany A=2 Introduction Few-Nucleon Systems and BBN Network n-p capture reaction rate becomes a “baryometer” WMAP determines Light-element abundances depends on and 11 nuclear reaction rates ( d, p ) ( p, γ ) ( d, n ) ( n, γ ) ( n, p ) ( d, p )

Sept. 1, Few-Body 19 Bonn, Germany Understanding the photodisintegration of the deuteron In 1936, H. A. Bethe and R. F. Bacher wrote … “… the transition from the ground state to the state of positive energy... can be produced by a magnetic moment, this ‘magnetic dipole’ photoelectric effect is, however, small compared to the ‘electric dipole’ effect …, except for very low energies... the final state must be a P-state” [ Rev. Mod. Phys. 8, (1936) ]

Sept. 1, Few-Body 19 Bonn, Germany In the near-threshold region, the photodisintegration cross section can be expanded in terms of S and P wave amplitudes. We can ignore the D-waves and The P-wave splittings (evidence will be presented soon) : Photon analyzing power measurement is proportional to the %E1 contribution to the total cross section The A=2 Experiments at HI  S Bethe, 1936

Sept. 1, Few-Body 19 Bonn, Germany A=2 Global Impact (Ahmed et al.) First-ever indirect determination of  0 for deuteron at low energies Ahmed et al. [PRC 77, (2008)]