1. V riunione nazionale di astrofisica nucleare
Teramo,  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. 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

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

5. Coulomb barrier & electron screening
Future 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

6. 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

7. 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 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

8. Underground N.A.
LNGS

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

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. 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

12. Motivations FB depends on nuclear physics and astrophysics inputs
FB= FB (SSM) · s s 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

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%]
Adopted
S34=(0.53±0.05) keV·b [9%]
NACRE 99
S34=(0.54±0.09) keV·b [16%]

15. Summary of previous measurements
M. Hass
NIC8

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

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

18. 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)

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

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

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

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

23. 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

24. 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)

25. 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

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
LUNA range: 300 – 70 keV Ec.m.
Courtesy of Michael Heil, Forschungszentrum Karlsruhe

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

30. 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

31. 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)
Lowest energy directly investigated: 940 keV c.m.

32. A new underground facility…
Requirements
Alpha beam: Ea = 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 /28
Courtesy of Wick Haxton, Univ. of Washington

34. 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
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 ….