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The HRIBF

Virtual HRIBF Tour 2. Study of 7 Be(p,  ) 8 B at the HRIBF 3. A novel approach to (p,  ) reactions Jeff Blackmon Physics Division, Oak Ridge National Lab. The HRIBF. SNO. 1998. SNO  NC = (5.21  0.27 stat  0.38 sys ) x 10 6 /(cm 2 s).

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The HRIBF

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  1. Virtual HRIBF Tour2. Study of 7Be(p,)8B at the HRIBF3. A novel approach to (p,) reactionsJeff BlackmonPhysics Division, Oak Ridge National Lab

  2. The HRIBF

  3. SNO 1998 SNO NC = (5.21  0.27stat 0.38sys) x 106 /(cm2s) SNO & SuperK measure only neutrinos from the decay of 8B 2. Flux measurements determine neutrino properties n 7Be(p,g)8B A accurate value for the predicted 8B neutrino flux is need for comparison to the current generation of measurements SuperK CC = (2.39  0.03stat 0.06sys) x 106 /(cm2s) Creighton Nickel Mine 1 kt heavy water nx + d  p + n SSM = 5.7 x 106 /(cm2s)  ~12-16%

  4. Trache (Glauber 2004) Schumann (CD 2003) Davids & Typel (CD 2003) Azhari (ANC 2001) Status of 7Be(p,g)8B Junghans et al. Evaluated S17 (eV b) Junghans PRC 68 (2003) 065803. 21.40.50.6 Davids & Typel PRC 68 (2003) 045802. 18.60.41.1 Cyburt et al., PRC 70 (2004) 045801. 19.3  21.4 with ~ 6-7%  • Precision has been significantly improved. • Some questions remain.

  5. New Coulomb dissociation result Schumann et al., PRC 73 (2006) 015806. Small E2 Change in S17(E) 20.60.81.2 eV b

  6. collimated Si detectors diagnostics 7Be H2 5+ p(8B) = p(7Be)  0.4% q(8B) < 0.24 v(7Be) = 1.14 v(8B) ionization chamber 8B s = H I7 e cm2 1H(7Be,8B) at the HRIBFala NABONA 4+ Transfer reactions Fusion evaporation Scattering reactions Energy loss & stopping power 12C(p,)13N 24Mg(p,g)25Al • Accurate statistics • Different, well-characterized systematic uncertainties

  7. Li metal 12 MeV protons ~ 10 mA 7Li(p,n)7Be 0.2 Ci 7Be beam production 2x1077Be/s 0.12 Ci

  8. Windowless H2 gas target Si detector  DE=3966 keV 19F(p,ag)16O e = (572) 10-15 eVcm2 n = DE /e n5.5 Torr = (6.95 ± 0.24)·1018 /cm2

  9. Stable capture reactions broad resonance narrow resonance scan qlab< 0.63 accepted by gas target apertures wg = 520  35 eV NACRE: 532  41 eV TRIUMF: 576  41 eV 24Mg(p,g)25Al shape very sensitive to losses < few %

  10. First 7Be(p,)8B run at the HRIBF Mixed 7Be & 7Li beam D2 gas 63.1 h<I> = 1.52x1077Be/sE(7Be) = 11.96  0.02 MeV Mixed 7Be & 7Li beam H2 gas Pure 7Li beam H2 gas 22 counts

  11. Junghans et al. 0.91 0.03 mb Results from first run New beam sampler R.P. Fitzgerald Ph.D. UNC (2005) New stable beam studies (Seattle) • Working on increasing beam intensity • More activity: ORIC & Debrecan • Cathode geometry (~2x) • Low energy beam transport (?) • 40 counts/day (1 MeV) • 10 counts/day (0.3 MeV) 8x1077Be/s (5x)

  12. 3. The 180-keV resonance in 17O+p 17O(p,)14N at CSNSM-Orsay 17O(p,)18F at LENA 17O(p,)14N rate increased by ~100 times Chafa et al., PRL 95 (2005) 031101. 18F production reduced by ~3-8 times in novae Fox et al., PRC 71 (2005) 055801.

  13. YY1 17O,12C Differential pumping CD  17O 14N C foil 10 g/cm2 Roots pumps 4 Torr H2 10 cm 15 10 log counts Strip # 5 1 0 20 40 60 80 100 z-distance (mm) 0 1 2 3 E-YY1 (MeV) 3 Novel approach to(p,) resonances 2 S1 E-CD (MeV) 1 17O(p,)14N <50 mT 0 0 1 2 3 E-YY1 (MeV) 3.32 MeV 3.34 MeV ~25% of 4 E strip #  vertex

  14. Stopping power for 17O in H2 • Stopping power for oxygen ions in H2 gas determined from position of resonance • Position of resonance determined independently from  and 14N kinematics 62(10-15) eVcm2 14.3 mm (631) x 10-15 eVcm2 At 195 keV/u (near peak) 64(10-15) eVcm2 SRIM 2003: 60 x 10-15 eVcm2

  15. 4 Torr Results 1 Torr • Consistent resonance strength found independent of position or pressure “on resonance” • Precision limited primarily by stopping powers • 20 keV beam energy loss (at P~4 Torr) before chamber • Results agree with Chafa et al. +0.1 -0.4 6% α+12C stopping 3% α strength 5% 17O+H2 stopping

  16. 2. 7Be(p,)8B Summary & Outlook • Mach I - 24% uncertainty at Ecm ~ 1.5 MeV • Systematic uncertainties less than 5% within reach • Mach II planned - 5% measurement at Ecm ~ 1.0 MeV • 10 days of beam time at 8x107 pps • Mach III? 3. (p,) reactions • Sensitive approach developed for narrow resonances • High yield: 25% 4 pure H2 target (3x) • Low background • 183 keV resonance in 17O(p,)14N measured • Results in good agreement with Chafa et al. • Submitting proposal to apply this approach to narrow resonances in 18F(p,)15O (287 keV and 330 keV)

  17. Thanks HRIBF StaffDOE Office Nuclear Physics 2. 7Be(p,)8B • R.P. Fitzgerald (UNC Grad Student) • D.W. Bardayan, J.C. Blackmon, K.Y. Chae, A.E. Champagne, U. Greife, K.L. Jones, R.L. Kozub, R.J. Livesay, Z. Ma, C.D. Nesaraja, S.D. Pain, F. Sarazin, M.S. Smith, D.W. Stracener, J. S. Thomas, D. W. Visser 3. (p,) reactions • B.H. Moazen (UT Grad Student) • D.W. Bardayan, J.C. Blackmon, K.Y. Chae, K. Chipps, C.P. Domizioli, R. Fitzgerald, U. Greife, K.L. Jones, R.L. Kozub, R.J. Livesay, C.D. Nesaraja, S.D. Pain, J.F. Shriner Jr., M.S. Smith, J. S. Thomas

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