Recent Experiments Involving Few-Nucleon Systems Werner Tornow Duke University & Triangle Universities Nuclear Laboratory Outline • A=3 systems g-3He 3-body breakup, n-n QFS in n-2H breakup, g-3H.
Download ReportTranscript Recent Experiments Involving Few-Nucleon Systems Werner Tornow Duke University & Triangle Universities Nuclear Laboratory Outline • A=3 systems g-3He 3-body breakup, n-n QFS in n-2H breakup, g-3H.
Recent Experiments Involving Few-Nucleon Systems Werner Tornow Duke University & Triangle Universities Nuclear Laboratory Outline • A=3 systems g-3He 3-body breakup, n-n QFS in n-2H breakup, g-3H three-body breakup • A=4 systems N-3He Ay(q) elastic, n-3H s(q) elastic (using Inertial Confinement Fusion (ICF)) • A=5 systems 3H(d,g)5He/3H(d,n)4He branching ratio (using ICF) • A=6 systems 3H(t,2n)4He neutron spectrum (using ICF) • A=12 system 12C(g,3a) and the 2+ excitation of the Hoyle 0+ state in 12C • Outlook and Conclusion Energy range considered: 50 MeV/N 1 A=3 g + 3He -> p + p + n 2 High-Intensity Gamma-ray Source (HIgS) @ TUNL 0.18-0.28 GeV Electron Linac 0.18-1.2 GeV Booster Injector 0.24-1.2 GeV Storage Ring g-ray beam parameters FEL Undulators World’s most intense accelerator-driven g-ray source Intensity 103 g/s/eV on target 3 Values Energy 1 – 100 MeV Linear & circular polarization > 97% Spatial distribution after collimation (diameter) 10 – 25 mm Pulse width (FWHM) 0.5 – 0.8 ns Pulse repetition rate 5.58 MHz Flux with 2% Eg/Eg ( 2 MeV < Eg < 5 MeV) > 3 × 106 g/s Flux with 5% Eg/Eg (5 MeV < Eg < 20 MeV) > 7 × 107 g/s 7 Intensity HIgS: Intracavity Compton-Back Scattering 2500 Eg =2032 keV 1500 Eg =26 keV E/E = 1.3% 500 1950 2000 2050 Eg (keV) Head-on collision: Eg ≈ 4γ2ħω Example: Ee = 500 MeV g = 978 lFEL = 400 nm ħω = 3.11 eV Eg = 11.9 MeV Vladimir Litvinenko 4 Three-body photodisintegration of 3He with double polarizations at 12.8 and 14.7 MeV at HIGS/TUNL facility (Haiyan Gao’s group) We detect neutrons! o Two Primary Goals: o Test state-of-the-art three-body calculations made by Deltuva [1] and Skibiński [2], and future EFT calculations. o Important step towards investigating the GDH sum rule for 3He below the pion production threshold : I GDH = thr d P 4 2a 2 A s N s N = NI 2 MN Lorentz & gauge invariance, crossing symmetry, causality and unitarity of the forward Compton scattering amplitude [1] A. Deltuva et al., Phys. Rev. C 71, 054005 (2005); Phys. Rev. C 72, 054004 (2005) and Nucl. Phys. A 790, 344c (2007). [2] R. Skibiński et al., Phys. Rev. C 67, 054001 (2003); R. Skibiński et al. Phys. Rev. C 72, 044002 (2005); R.Skibiński. Private communications. Gerasimov-Drell-Hearn 5 Goal II: GDH Sum Rule on 3He d 2 2 a 2 P A s N s N = N 2 MN thr thr thr 496b GDH 3 He 217 39b ?? HIγS @ TUNL GDH 3 He 2 3GeV A. Deltuva Extrapolated from low Q2 3He GDH (E94-010) measurement @ JLab, (E97-110 much lower Q2) 247 38b GDH 3 He 2 3GeV GDH 3 He 31.9 9.6b23GeV GDH 3 He = Pn 23GeV GDHn 2 Pp 23GeV GDH p = 0.87 35 2 (0.027) (26) M. Amarian, PRL 89, 242301(2002) J.L. Friar et al. PRC 42, 2310 (1990) N. Bianchi, et al. PLB 450, 439 (1999) 6 Apparatus of the Three-body Photodisintegration Experiment Beam Direction Optics Table Beam enclosed in vacuum Laser light D2O cell-flux monitor not shown in the schematic 1. Automatically movable target and optical table 2. Detectors in mu-metal shielding tubes 7 High-pressure hybrid 3He target polarized longitudinally using spin-exchange optical pumping 7 atm 40 cm long Pyrex glass tube grays 8 9 Spin-Dependent Double Differential Cross Sections at 12.8 MeV Solid curve: R. Skibiński et al. Dotted curve: A. Deltuva , A. Fonseça 10 Spin-Dependent Single Differential Cross Sections at 12.8 MeV (preliminary) 11 Spin-Dependent Total Cross Sections and the GDH Integrand This work 12.8 Deltuva et al. 872 777 0.146 956 872 0.131 1026 900 0.168 1079 970 0.146 This work 14.7 Deltuva et al. Deltuva et al. Skibiński et al. Only 3-body part 10 year effort ! G. Laskaris et al., Phys. Rev. Lett. 110, 202501 (2013) 12 A=3 nn QFS in n + d breakup & g + 3H three-body breakup 13 En=26 MeV n+d >n+n+p n-p QFS 2H(d,n)3He W. von Witsch, A. Siepe et al., 2002 For n-n QFS the proton detector is replaced by a neutron detector 14 W. von Witsch, A. Siepe et al. (Bonn) 2H(n,np)n np QFS H. Witała En=26 MeV 2H(n,nn)p nn-QFS H. Witała 15 En=25 MeV X.C. Ruan (CIAE) & W. von Witsch (Bonn), 2007 China Institute of Atomic Energy 2H(n,nn)p nn-QFS H. Witała 3H(d,n)4He 16 En=19 MeV TUNL np and nn QFS experimental setup Proton Detector Neutron Detector Transmission Foil Detector 2H(d,n)3He Pulsed Deuteron Beam Neutron Beam Deuterium Gas Cell C6D12 Target CD2 Target Proton Recoil Telescope Neutron Detector Collimator & Shielding Wall np QFS setup Neutron Detector nn QFS setup 1.5 m 17 18 H. Witała & W. Glöckle 19 Parallel Session B1 (Monday afternoon) Di-neutron searches Yushi Maeda Kazimierz Bodek Sergey Zuyev 2H(n,p)nn -absorption on 3He and 4He d + T -> 3He + 2n 20 3H(g,p)nn 3H(g,n)2H R. Skibiński 21 Photon induced three-body breakup of 3H > n +n +p -108 keV -323 keV H. Witała 22 23 A=4 N – 3He Analyzing Power Ay(q) at low energies 24 p – 3He McDonald 1964 Fisher 2006 Alley 1993 Entem&Machleidt Doleschall A. Deltuva 25 n - 3He En=1.60 MeV dashed green INOY04 dashed blue AV18 En=2.26 MeV En=4.05 MeV solid orange CD Bonn En=5.54 MeV dotted red CD Bonn + A. Deltuva En=3.14MeV J. Esterline et al., PRL 110,152503 ( 2013) 26 Nucleon-3He elastic scattering CD Bonn, 7.26 MeV INOY04, 7.73 MeV p-3He p-3He n-3He n-3He 27 Four-Nucleon Elastic Scattering p - 3He T=1 n - 3H T=1 p - 3H T=0,1 n - 3He T=0,1 need data need better data 28 A=4 n -3H elastic s(q) at 14.1 MeV from Inertial Confinement Fusion (ICF) OMEGA @ University of Rochester 29 30 kJ 1-ns square pulse Yn = 5×1013 <Ti>n = 9 keV qnt SiO2 glass shell burnt away entirely at bang time n' DT 3.5 m SiO2 20 atm DT gas t’ n n n' 425 m qnd d’ Elastically-scattered deuterons (d’): n(14.1MeV) + D n’ + d’ (<12.5 MeV) Ed’ = (8/9) × En × Cos2qnd Elastically-scattered tritons (t’): n(14.1MeV) + D n’ + t’ (<10.5 MeV) Et’ = (3/4) × En × Cos2qnt Plasma serves as both neutron source and target 30 J. Frenje Simultaneous measurements of the d’ and t’ spectra were conducted with a simple magnetic spectrometer (CPS2) Target CPS2 50keV (p) 2cm 30 MeV (p) 15 MeV (d) 10 MeV (t) 3 MeV (p) OMEGA-target chamber 60 laser beams DD-p spectrum was also measured for reference CR-39: d’ : 3.7 – 12.5 MeV t‘ : 2.5 – 10.5 MeV F.H. Séguin et al., Rev. Sci. Instrum 74, 975 (2003) 31 J. Frenje d’ and t’ spectra were obtained by selecting signal and background areas and putting constraints on the diameters and darkness of the signal tracks d’ d’-high-energy peak Bkgd areas n,2n-p d’-signal area t’ Y t’-signal area X (energy) t’-high-energy peak 32 d’ J. Frenje d’ and t’ spectra were obtained simultaneously on three OMEGA shots The n-t differential cross section was obtained by deconvolving the Doppler broadening and CPS2-response function. The well known n-d differential cross section was used for absolute normalization of the n-t cross section. 33 J. Frenje n-d n-t NCSM ab-initio theory3 Faddeev calculation1 1 E. Epelbaum et al., PRC 66, 064001 (2002). 2 3 J.A. Frenje et al., PRL 107, 122502 (2011). P. Navrátil et al., LLNL-TR-423504 (2010). 34 A=5 3H(d,g)5He/3H(d,n)4He gamma-to-neutron branching ratio from Inertial Confinement Fusion (ICF) National Ignition Facility (NIF) Lawrence Livermore National Laboratory 35 National Ignition Facility (NIF) at LLNL Inertial Confinement Fusion, 192 laser beams, DT capsule in hohlraum 36 Neutron and g-ray spectrometry typically used to support the ICF program have been used to explore basic nuclear physics on NIF (and OMEGA) MRS (77-324) nTOF4.5m (64-330) nTOF3.9m (64-275) Spec-E (90-174) NITOF (90-315) Cross cut image of the NIF chamber Spec-A (116-316) M. Gatu Johnson et al., RSI (2012). F.E Merrill et al., RSI (2012). 37 38 Y. Kim et al. Phys. Rev. C 85, 061601(R), 2012 New accelerator driven efforts are underway Ohio University 39 A=6 T + T neutron spectrum from OMEGA and NIF 40 The T+T reaction has been studied extensively at OMEGA and NIF 4 μm SiO2 10 atm DT 10 μm CD Possible reactions: 12 atm DT OMEGA 15 μm CH 17 atm DT 20 μm CH 17 atm DT 41 + T → 4He + 2n (0-9.5 MeV) T + T → 5He + n (8.7 MeV) T + T → 5He* +n Understanding the T+T reaction at low CM energies has important implications for: 1. Nuclear physics 2. Stellar nucleosynthesis [3He(3He,2p)4He] 3. HEDP/ICF ~230 µm CH 4 atm at 32 K T2 T NIF J. Frenje Casey measured the T+T neutron spectrum for the first time using ICF 3.0 n+5He dN / dE [au] n+n+4He Wong (1965) Allen (1951) Casey (2012) 2.0 ECM = 250 keV ECM = 110 keV 1.0 ECM = 23 keV 0 0 5 10 Neutron energy [MeV] Casey’s measurement was conducted at poor energy resolution, which washes out a possible weak n+5He resonance (<5%). 15 Casey et al, PRL (2012). Allen et al, PR (1951). Wong et al, NP (1965). 42 Casey’s measurement was later improved by high-resolution measurements of the T+T neutron spectrum at NIF / OMEGA G. Hale R-matrix modeling 43 A=12 Nuclear Astrophysics The 2nd 2+ state in 12C 44 Red giant stars Resonance enhancement is needed. Nature forms 8Be (ground state is a resonance 92 keV above the 4He-4He threshold). Helps, but not sufficient. Hoyle (1954) proposed a resonance in 12C just above the combined mass of 8Be and a-particle. Observed in 1957. 45 Nuclear Astrophysics & EFT Lattice Calculations A 22+ state in 12C was predicted by Morinaga (Phys. Rev. 101, 1956) as the first rotational state of the “ground” state 7.654 MeV (Hoyle State) Hoyle Recently, Epelbaum, Krebs, Lee, Meißner (Phys. Rev. Lett. 106, 192501, 2011) have performed Ab Initio Chiral Effective Field Theory Lattice calculations for the Hoyle State and its structure and rotations. Epelbaum et al. Phys. Rev. Lett. 109 252501 (2012) 46 Evidence of 2nd 2+ state in 12C Optical Time Projection Chamber (OTPC) M. Gai et al. Gas (Target/Detector) filled volume (CO2+N2) Grid provides the total energy (E/E of 4 %) PMTs provide the Time-Projection (10 ns bins): out-of-plane angle of the track Optical Readout provides the track image: in-plane angle of the track g + 12C > 3a 47 48 49 50 Evidence of a New 22+ State in 12C: Results Experiment: Comparing the Experimental Results and the lattice EFT Calculation Experiment Theory E(22+ - 02+) B(E2: E(22+ 01+) 2.37 ± 0.11 2.0 ± 1 to 2 0.73 ± 0.13 2±1 51 53 54 Nuclear Astrophysics Impact of the 22+ State o Helium burning occurs at a temperature of 108–109K, and is completely governed by the Hoyle state; o However, during type II supernovae, g-ray bursts and other astrophysical phenomena, the temperature rises well above 109 K, and higher energy states in 12C can have a significant effect on the triple-a reaction rate; o Preliminary calculations suggest a dependence of high mass number (>140) abundances on the triple alpha reaction rate based on the parameters of the 22+ state. 55 Outlook What’s next at TUNL ? 56 Few-Body Physics Studies at HIGS o HIGS is currently mounting the GDH experiment on the deuteron o Installation of the HIGS Frozen Spin Target (HIFROST) is ongoing o The majority of data taking will be completed by the end of 2013 between 4 and 16 MeV Phys. Rev. C78, 034003 (2008) Phys. Rev. C77, 044005 (2008) 57 Gerasimov-Drell-Hearn Sum Rule on the Deuteron I GDH = thr Ip=204.8 b 2 d P 4 a 2 A s N s N = NI 2 MN In=232.5 b Id=0.652 b Above pion production threshold: Large positive value Below pion production threshold: Large negative value 58 Setup for GDH Measurement on Deuteron Frozen-spin polarized target HIFROST 59 Compton Scattering The T-matrix for the Compton scattering of incoming photon of energy w with a spin (s) ½ target is described by six structure functions e = photon polarization, k is the momentum 60 HIGS Results on 16O and 6Li Compton Scattering 16O 6Li Phenomenological Model o Giant Resonances o Quasi-Deuteron o Modified Thompson 61 BcPT with Prediction a = 10.7 ± 0.7 b = 4.0 ± 0.7 PDG Accepted Value a = 12.7 ± 0.6 b = 1.9 ± 0.5 62 What’s next elsewhere at low energies? ICF facilities may play a major role in experimental Few-Body Physics 63 HIgS2 Layout e-beam Laser beam -ray Collaborators: Jun Ye, JILA and U. of Colorado at Boulder Mirrors of FP optical cavity Lcav = 1.679 m PFB (avg) > 10 kW, 90 MHz 64 What’s new beyond the next 5 years: HIgS2 Comparison of HIgS2 to ELI ELI: Extreme Light Infrastructure Bucharest, Prague, Szeged 65 Backup Slides Nucleon-3He A=4 elastic scattering CD Bonn p-3He n-3He INOY04 p-3He n-3He p-3H p-3H from W. Tornow et al., Phys. Lett. B 702, 121 (2011) 68 The Few-Body System: 4He Inconsistencies ! World Data on 4He(g,n)3He 4He(g,p)3H References: Raut et al., PRL, 108, 042502 (2012), and Tornow et al., PR C85, 061001R (2012) The Few-Body System: 4He Results from HIGS The Few-Body System: 4He Results from HIGS