Few-Body HIgS

Transcription

1 Few-Body HIgS Werner Tornow Duke University & Triangle Universities Nuclear Laboratory

2 Outline High-Intensity Gamma-ray Source (HIgS) A=3 g- 3 He three-body breakup with double polarization Outlook g- 3 H three-body breakup Gerasimov-Drell-Hearn Sum Rule of the deuteron Compton scattering off the proton, deuteron and 3 He Future Upgrade (A=12 system) 12 C(g,3a) and the 2 + excitation of the Hoyle 0 + state in 12 C 1

3 High-Intensity Gamma-ray Source TUNL GeV Booster Injector GeV Electron Linac GeV Storage Ring g-ray beam parameters Values Energy MeV Linear & circular polarization > 97% FEL Undulators Spatial distribution after collimation (diameter) Pulse width (FWHM) Pulse repetition rate mm ns 5.58 MHz World s most intense accelerator-driven g-ray source Intensity 10 3 g/s/ev on target 2 Flux with 2% E g /E g ( 2 MeV < E g < 5 MeV) > Flux with 5% E g /E g (5 MeV < E g < 20 MeV) > Flux on with 5% E g /E g (20 MeV< E g < 100 MeV) g/s g/s > g/s

4 Intensity HIgS: Intracavity Compton-Back Scattering E g =2032 kev E g =26 kev E/E = 1.3% E g (kev) Head-on collision: E g 4γ 2 ħω Example: E e = 500 MeV g = 978 l FEL = 400 nm ħω = 3.11 ev E g = 11.9 MeV Vladimir Litvinenko 3

5 A=3

6 World Data HIgS Data from W. Tornow et al., Phys. Lett. B 702, 121 (2011) 4

7 World Data HIgS Data Lorentz Integral Transform Trento Group Giant Dipole Resonance Wataru Horiuchi from R. Raut, W. Tornow et al., PRL, 108, (2012) 5

8 World Data HIgS Data 4 He(g,n) 3 He from W. Tornow et al., PR C85, R (2012) 6

9 A=3 g + 3 He -> p + p + n 7

10 Three-body photodisintegration of 3 He with double polarizations at 12.8 and 14.7 MeV at HIGS/TUNL facility (Haiyan Gao s group) o Two Primary Goals: o o Test state-of-the-art three-body calculations made by Deltuva [1] and Skibiński [2], and future EFT calculations. Important step towards investigating the GDH sum rule for 3 He below the pion production threshold : I GDH = thr d 2 P A 4 a 2 = I N Lorentz & gauge invariance, crossing symmetry, causality and unitarity of the forward Compton scattering amplitude N M 2 N N We detect neutrons! [1] A. Deltuva et al., Phys. Rev. C 71, (2005); Phys. Rev. C 72, (2005) and Nucl. Phys. A 790, 344c (2007). [2] R. Skibiński et al., Phys. Rev. C 67, (2003); R. Skibiński et al. Phys. Rev. C 72, (2005); R.Skibiński. Private communications. Gerasimov-Drell-Hearn 8

11 Goal II: GDH Sum Rule on 3 He A. Deltuva thr d thr P A 2 = N GDH 3 He N 2 2 a M 2 N N 496b b?? TUNL 23GeV thr GDH 23GeV 3 He GDH GDH 3 3 He He b 9.6b Extrapolated from low Q 2 3 He GDH (E94-010) JLab, (E much lower Q 2 ) 3 GDH = Pn GDHn P He p 3 = ( 0.027) ( 26) GeV 2 GeV 23GeV GDH p M. Amarian, PRL 89, (2002) J.L. Friar et al. PRC 42, 2310 (1990) N. Bianchi, et al. PLB 450, 439 (1999) 9

12 Intensity HIgS: Intracavity Compton-Back Scattering E g =2032 kev E g =26 kev E/E = 1.3% E g (kev) Head-on collision: E g 4γ 2 ħω Example: E e = 500 MeV g = 978 l FEL = 400 nm ħω = 3.11 ev E g = 11.9 MeV Vladimir Litvinenko 10

13 Beam Direction Apparatus of the Three-body Photodisintegration Experiment 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 11

14 High-pressure hybrid 3 He target polarized longitudinally using spin-exchange optical pumping 7 atm grays 40 cm long Pyrex glass tube 12

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16 Spin-Dependent Double Differential Cross Sections at 12.8 MeV Solid curve: R. Skibiński et al. Dotted curve: A. Deltuva, A. Fonseça 14

17 Spin-Dependent Single Differential Cross Sections at 12.8 MeV 15

18 Spin-Dependent Total Cross Sections and the GDH Integrand This work 12.8 Deltuva et al This work 14.7 Deltuva et al Deltuva et al. Skibiński et al. Only 3-body part 10 year effort! 2-body part next G. Laskaris et al., Phys. Rev. Lett. 110, (2013) 16

19 Deltuva 17

20 Outlook What s next at HIgS? 18

21 A=3 g + 3 H three-body breakup 19

22 Emiko Hiyama 20

23 E n =26 MeV n + d > n + n + p n-p QFS 2 H(d,n) 3 He W. von Witsch, A. Siepe et al., 2002 For n-n QFS the proton detector is replaced by a neutron detector 21

24 W. von Witsch, A. Siepe et al. (Bonn) E n =26 MeV 2 H(n,np)n np QFS 2 H(n,nn)p nn-qfs H. Witała H. Witała 22

25 E n =25 MeV X.C. Ruan (CIAE) & W. von Witsch (Bonn), 2007 China Institute of Atomic Energy 2 H(n,nn)p nn-qfs H. Witała 3 H(d,n) 4 He 23

26 n+d = n + n + p versus g+ 3 H=n + n + p 24

27 Photon induced three-body breakup of 3 H > n +n +p H. Witała kev -323 kev

28 3 H Holder 26

29 A=2 g + 2 H breakup 27

30 Gerasimov-Drell-Hearn Sum Rule on the Deuteron I GDH = thr d P A 2 = I N N 4 2 M a 2 N N I p =204.8 b I n =232.5 b I d =0.652 b Above pion production threshold: Large positive value Below pion production threshold: Large negative value 28

31 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 2014 between 4 and 16 MeV Phys. Rev. C78, (2008) Phys. Rev. C77, (2008) 29

32 Setup for GDH Measurement on Deuteron Frozen-spin polarized target HIFROST 30

33 Compton Scattering: A=1, A=2, A=3 31

34 32 Compton Scattering The T-matrix for the Compton scattering of incoming photon of energy w with a spin () ½ target is described by six structure functions e = photon polarization, k is the momentum

35 HIGS Results on 16 O and 6 Li Compton Scattering 16 O 6 Li Phenomenological Model o Giant Resonances o Quasi-Deuteron o Modified Thompson 33

36 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 Polarizabilities 34

37 Upgrade of HIgS: HIgS2 35

38 HIgS2 Layout e-beam Laser beam g-ray Collaborators: Jun Ye, JILA and U. of Colorado at Boulder Mirrors of FP optical cavity L cav = m P FB (avg) > 10 kw, 90 MHz 36

39 Major physics drivers 1. g + 16 O = 12 C + a Holy Grail of Nuclear Astrophysics) 2. g d = n + p (Parity violation) 37

40 Comparison of HIgS2 to ELI ELI: Extreme Light Infrastructure Bucharest, Prague, Szeged 38

41 Backup slides

42 A=12 Nuclear Astrophysics The 2 nd 2 + state in 12 C 40

43 Red giant stars Resonance enhancement is needed. Nature forms 8 Be (ground state is a resonance 92 kev above the 4 He- 4 He threshold). Helps, but not sufficient. Hoyle (1954) proposed a resonance in 12 C just above the combined mass of 8 Be and a-particle. Observed in

44 Nuclear Astrophysics & EFT Lattice Calculations Hoyle A 2 2+ state in 12 C was predicted by Morinaga (Phys. Rev. 101, 1956) as the first rotational state of the ground state MeV (Hoyle State) Recently, Epelbaum, Krebs, Lee, Meißner (Phys. Rev. Lett. 106, , 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 (2012) 42

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47 Evidence of 2 nd 2 + state in 12 C Optical Time Projection Chamber (OTPC) M. Gai et al. Gas (Target/Detector) filled volume (CO 2 +N 2 ) 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 + 12 C > 3a 45

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51 Evidence of a New State in 12 C: Results Experiment: Comparing the Experimental Results and the lattice EFT Calculation E( ) B(E2: E( ) Experiment 2.37 ± ± 0.13 Theory 2.0 ± 1 to 2 2 ± 1 49

52 Nuclear Astrophysics Impact of the 2 2+ State o Helium burning occurs at a temperature of K, 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 10 9 K, and higher energy states in 12 C 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 2 2+ state. 50