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Sviluppi futuri degli esperimenti di astrofisica nucleare in Italia

V riunione nazionale di astrofisica nucleare Teramo,  20-22 aprile, 2005. Sviluppi futuri degli esperimenti di astrofisica nucleare in Italia. Paolo Prati. Experimental Nuclear Astrophysics in Italy.

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Sviluppi futuri degli esperimenti di astrofisica nucleare in Italia

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  1. V riunione nazionale di astrofisica nucleare Teramo,  20-22 aprile, 2005 Sviluppi futuri degli esperimenti di astrofisica nucleare in Italia Paolo Prati

  2. Experimental Nuclear Astrophysics in Italy In the future experimental groups will concentrate their activities on facilities at two INFN National Labs: Catania (LNS) Gran Sasso (LNGS)

  3. on source Dynamitron tandem accelerator recoil transport Magnetic quadrupole multipletts beam purification g - raydetection gastarget DE-E Detector Wien filter Wien filter recoilseparation 60° dipole magnet ERNA (present) setup

  4. Future activities @ LNS A recoil separator, ERNA, will be installed at the new RIB facility, EXCYT, at LNS

  5. spectator s A participant x c a C A VFm a x s Vrel=Va-VFm~ 0 Eax0 astrophysical energies Future activities @ LNS:Trojan Horse Method quasi-free interaction three body reaction a + A  c + C + s A cluster ofx  s To study a + x  c + C of astrophysical interest if: Ea >> Ecoul Coulomb barrier & electron screening negligible

  6. Trojan Horse Method 3-body cross section measured by the coincidences of c and C Calculation of the 2-body cross section for bare nuclei s astrophysics smeasured KF= kinematic factor |G(Ps)|2= momentum distribution of x in A

  7. a 6Li d 4He p 3He sub-barrier reonance at~150 kev n d THM data p 8Be a 11B 3He(d,p)4He 6Li =d a The 200 keV resonance, due to the 16.87 MeV level of 5Li, has been reproduced 11B(p,a0)8Be d =p  n The 150 keV resonance, due to the 16.1 MeV level of 12C, has been reproduced Courtesy of Claudio Spitaleri, INFN -LNS

  8. Underground N.A. LUNA @ LNGS

  9. Laboratory for Underground Nuclear Astrophysics Gran Sasso National Laboratory (LNGS) Cosmic background reduction: g: 10-6 n: 10-3 3He(3He,2p)4He d(3He,p)4He 50 KV : (1992-2001) d(p,g)3He 14N(p,g)15O (CNO cycle) 400 KV: (2000-2004)

  10. LUNA:400 kV accelerator • Umax= 50 – 400 kV • I 500 A for protons I 250 A for alphas • Energy spread : 72eV • Total uncertainty is 300 eV between Ep = 100  400keV

  11. p,g 12C 13N p + pd + e+ + ne b- p,a d + p3He + g pp chain CNO cycle 84.7 % 13.8 % 15N 13C 3He +3He a + 2p 3He +4He7Be+g p,g b+ 0.02 % 13.78 % 15O 14N 7Be+e-7Li+g+ne 7Be +p8B+g p,g 7Li +pa+ a 8B2a+ e++ ne LUNA + ERNA Present/next-future program

  12. Motivations • FB depends on nuclear physics and astrophysics inputs • FB= FB (SSM)· s33-0.43 s34 0.84 s171 se7-1 spp-2.7 • · com1.4 opa2.6 dif 0.34 lum7.2 • These give flux variation with respect to the SSM calculation when the input X is changed by x = X/X(SSM) . • Can learn astrophysics if nuclear physics is known well enough. • Nuclear physics uncertainties, particularly on S34 , dominate over the present observational accuracyDFB/FB =7%. • The foreseeable accuracyDFB/FB=3%could illuminate about solar physics if a significant improvement on S34 is obtained Courtesy of Gianni Fiorentini, INFN-Ferrara

  13. 3He(a,g)7Be 7Be+e7Li*(g) Eg=1585 keV + Ecm (DC  0); Eg= 1157 keV + Ecm (C  0.429) Eg= 429 keV Eg = 478 keV

  14. 3He(a,)7Be 7Be+e7Li*() SEATTLE 98 S34=(0.572±0.026) keV·b [5%] S34=(0.507±0.016) keV·b [3%] Adopted S34=(0.53±0.05) keV·b [9%] NACRE 99 S34=(0.54±0.09) keV·b [16%]

  15. M. Hass NIC8 Summary of previous measurements

  16. Lead shield 1st 3rd 2nd HPGe @LUNA… Expected attenuation for 1.6 MeV gs: 10-5-10-6 (GEANT4 simulations)

  17. 3He(a,g)7Be: Target chamber Movable silicon detector for I*r meas. @LUNA… Removable calorimeter cap for off-line 7Be-activity measurement

  18. P = 1 mbar; I = 200 mA 1.6 MeV counts/day 1.2 MeV BCK HpGe Ecm [keV] Expected counting rate Gamow peak Lowest meas. point LUNA goal: a 3% precision on S(E)

  19. 3He(a,g)7Be: a new detector E-TOF to measure at Ecm< 1.5 MeV @ERNA… Ecm=0.4 MeV Ecm=1.2 MeV Courtesy of Lucio Gialanella, INFN - Napoli

  20. Next @ LUNA 25Mg(p,g)26Al Radioactive 26Al in the Galaxy

  21. Motivation for 25Mg(p,g)26Al

  22. (p,g) (p,g) 21Ne 22Na 25Mg 26Al (p,g) e+n e+n e+n e+n 26Mg 27Si 21Na 22Ne 25Al (p,g) (p,g) (p,g) (p,g) e+n 20Ne 19F 23Na 24Mg 27Al 28Si (p,g) (p,a) (p,g) (p,a) (p,g) NeNa and MgAl cycle Slowest reaction of MgAl cycle

  23. Massive stars Novae, Supernovae T 9≈ 0.05 T 9≈ 0.2 E p ≈ 200 keV E p ≈ 100 keV Calculations Experiments Possible 26Al production sites • Supernovae • Novae • Massive stars: AGB, Wolf-Rayet stars

  24. 25Mg(p,g)26Al RESONANCES Target: pure 25Mg Beam: 500 mA LUNA Limit ? Iliadis, Phys. Rev.C53 (1996)

  25. what else might be studied underground? Supernovae ~ He burning 12C(a,g), 16O(a,g) 14N(a,g) 18O(a,g) 22Ne(a,g) AGB stars ~ s process 14N(p,g) 17O(p,g) 17O(p,a) Red giants ~ CNO cycle 22Ne(p,g) 23Na(p,a) 24Mg(p,g) Globular clusters ~ Ne/Mg/Na cycles Supernova nucleosynthesis 20Ne, 24Mg, 28Si, 32S, 36Ar, 40Ca(a,g) Courtesy of J.C. Blackmon, Physics Division, ORNL

  26. Some selected cases at LENA Upper limit OK for LUNA: Eg > 4 MeV, I~ 300 mA Courtesy of Cristian Iliadis, Univ. of North Carolina

  27. Some selected cases at LENA EXIT from the “Ne/Na cycle” OK for LUNA: Eg > 4 MeV, I~ 250 mA, no coincidence needed! Courtesy of Cristian Iliadis, Univ. of North Carolina

  28. Another case: neutron source(s) for s-process Courtesy of Michael Heil, Forschungszentrum Karlsruhe LUNA range: 300 – 70 keV Ec.m.

  29. Courtesy of Michael Wiescher, Univ. of Notre Dame

  30. Reaction Mechanism s(E0) is expected to be dominated by E1 transition due to a broad 1- state (Ex=9585 keV, Ecm=2423 keV) and to the high energy tail of the sub-threshold 1- state (Ex=7117 keV, Ecm=-45 keV). An E2 transition comes from a 2+ state (Ex=6917 keV, Ecm=-245 keV). Direct capture also plays a role. E1 and E2 are expected to be comparable at E0. Rolfs & Rodney: Cauldrons in the cosmos

  31. 4 reaction/month with I ~ 1 mA !!!! s(300 keV) ~ 10-8 nb E1 S-Factor E2 S-Factor s(2423 keV) ~ 40/50 nb 12C(a,g)16O: S Factor Ouellet et al. Phy. Rev. C 54 4 (1996) 1982-1998 Lowest energy directly investigated: 940 keV c.m.

  32. Requirements Alpha beam: Ea = 0.2 - 3 MeV also for 22Ne(a,g), 22Ne(a,n), 40Ca(a,g) I beam ~ 1 mA DE/E ~ 10-3 – 10-4 Negligible beam induced background A new underground facility… Is it possible?

  33. News from USA A workshop to discuss “an underground accelerator for nuclear astrophysics” , Tucson 2003-11-27/28 Courtesy of Wick Haxton, Univ. of Washington

  34. The last idea… A new tunnel under Cashmere peak (Washington) a granite rock with a cover of 6421 feets (~ LNGS) Data taking from 2013.... Courtesy of Wick Haxton, Univ. of Washington

  35. Accelerator technology: The RFQ Beam energy is fixed • The RFQ provides rf longitudinal electric field for acceleration and transverse rf electric quadrupole field for focusing -ideal for acceleration of low-velocity high-current ion beams. Courtesy of Tom Wangler, LANL

  36. Suggestion: Continuous energy variability can be provided by installing the sectioned RFQ on a DC HV platform. By providing a variable HV platform voltage with a maximum value that exceeds the voltage gain of the individual RFQ sections, it should be possible to dial up any output energy by: • turning off appropriate number of downstream RFQ sections • adjusting the platform HV. • An RFQ design study should be carried out to answer questions such as current limits (10s of mA ), energy spread, energy variability, size, and AC power for normal-conducting and superconducting options. Courtesy of Tom Wangler, LANL

  37. At LNGS ? Several problems…. • Space required: 200 - 400 m2 • Possible background induced to other experiments • Budget ….

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