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 In the future experimental groups will concentrate their activities on facilities at two INFN National Labs: Catania (LNS) Gran Sasso (LNGS)

ERNA (present) setup beam purification Dynamitron tandem accelerator on source recoil transport Magnetic quadrupole multipletts Wien filter 60° dipole magnet recoil separation Wien filter DE-E Detector gas target g - ray detection

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

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

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

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

Underground N.A. LUNA @ LNGS

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 400 KV: (2000-2004) 14N(p,g)15O (CNO cycle)

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

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

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 accuracy DFB/FB =7%. The foreseeable accuracy DFB/FB=3% could illuminate about solar physics if a significant improvement on S34 is obtained Source DX/X (1s) DFB/FB (1s) S33 0.06 0.03 S34 0.09 0.08 S17 0.05 ? 0.05 Se7 0.02 Spp Com Opa Dif 0.10 Lum 0.004 Courtesy of Gianni Fiorentini, INFN-Ferrara

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

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

Summary of previous measurements M. Hass NIC8

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

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

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

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

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

Motivation for 25Mg(p,g)26Al

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

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

25Mg(p,g)26Al RESONANCES LUNA Limit ? Target: pure 25Mg Beam: 500 mA Ecm [keV] Ex [keV] Reaction per day 37.5 6343.5 3.65E-08 58.0 6364.0 2.80E-01 92.6 6398.6 7.35E+01 108.5 6414.5 1.64E+01 130.4 6436.4 6.80E+01 189.9 6495.9 2.68E+05 244.3 6550.3 1.53E+06 292.3 6598.3 1.32E+07 304.4 6610.4 8.55E+12 374.5 6680.5 1.62E+13 418.2 6724.2 2.78E+13 LUNA Limit ? Iliadis, Phys. Rev.C53 (1996)

what else might be studied underground? 20Ne, 24Mg, 28Si, 32S, 36Ar, 40Ca(a,g) Supernova nucleosynthesis what else might be studied underground? 12C(a,g), 16O(a,g) Supernovae ~ He burning 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 Courtesy of J.C. Blackmon, Physics Division, ORNL

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

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

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

Courtesy of Michael Wiescher, Univ. of Notre Dame

E1 and E2 are expected to be comparable at E0. 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

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

A new underground facility… 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?

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

The last idea… Data taking from 2013.... 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

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

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

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