Nuclear Astrophysics - Nuclear Physics

Nuclear Astrophysics
• energy generation in stars
• nucleosynthesis (primordial + stellar)
www.cyc.ucl.ac.be/CARINA
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Why are radioactive ion beams
needed in astrophysics?
average interaction time:
(half-life of X by interaction with Y )
τ ( X ) =
y
N
y
1
σ v
• Hydrostatic equilibrium: quiescent burning stages in stellar evolution
example p+p: T ~ 15x10 6 K, ρ=100 g/cm 3 ⇒ average interaction time τ ~ 10 9 y
additional example >>
• Explosive scenarios
T > 10 8 K, ρ>10 3 g/cm 3 (ex: WD surface) ⇒ average interaction time τ ~ sec
www.cyc.ucl.ac.be/CARINA
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Explosive burning - astrophysical sites
In explosive astrophysical sites such as the binary systems novae and X-ray bursters,
nucleosynthesis [ up to A ~ 60 (nova) and A ~ 80 – 100 (X-ray burst) ] is thought to be provided
by hydrogen and helium burning at high temperatures and densities. [J José et al. (1999), H Schatz et
al., (1998) ]
snapshots of a classical Nova outburst (courtesy of J José)
Hydrogen and helium rich material from a companion aging main sequence star piles up onto
the surface of a white dwarf (WD in nova) or neutron star (NS in X-ray burst) forming an
accretion disk.
The temperature and density increase in the surface of the WD (T>10 8 K, ρ>10 3 g/cm 3 ) or NS
(T>10 9 K, ρ>10 6 g/cm 3 ) generating a sudden increase of the star luminosity.
Critical T and ρ values: reactions involving H and He on nuclei ranging from C to Ca releasing
energy in a runaway thermonuclear explosion.
www.cyc.ucl.ac.be/CARINA
Source: Carmen Angulo (CARINA)

Novae & HCNO breakouts
(exact path depends on given stellar conditions)
26 Si
27 Si 28 Si
30
P(p,γ) 31 S
heavy nuclei
beyond S
25
Al(p,γ) 26 Si
24 Al
25 Al
26 Al
27 Al
rp-process
onset
21 Mg 22 Mg
23 Mg
24 Mg 25 Mg
26 Mg
18
F(p,α) 15 O
17
O(p,α) 14 N
breakout
from HCNO
20 Na
18 Ne 19 Ne
20 Ne
21 Na 22 Na
23 Na
21 Ne 22 Ne
NeNa
cycle
17
O(p,γ) 18 F
17
F 18 F
19 F
14
O
15
O
16 O 17 O 18 O
(α,p)
(p,γ)
(α,γ)
HCNO
13 N 14 N
15
N
(p,α)
(β + )
stable
12 C
13
C
unstable
www.cyc.ucl.ac.be/CARINA
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Novae nucleosynthesis
18
F(p,α) 15 O
25
Al(p,γ) 26 Si
30
P(p,γ) 31 S
17
O(p,γ) 18 F
17
O(p,α) 14 N …etc.
18 F: 10m 25 Al: 7.2s 30 P: 2.5m
Beams
Beam intensity
Energy range
Targets
Instrumentation
requesters
: 18 F, 25 Al, 30 P, 17 O
: more than 10 9 pps
: below 500 keV (CM)
: foils (problem of stability for high beam currents?);
gas targets needed?
: detectors, recoil separator
: Jordi José, Alain Coc
Examples of CARINA list of key-reactions
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ack to explosions
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Nucleosynthesis
Mixing
(abundance distribution)
Big-Bang & H-burning
interstellar
gas & dust
He burning
C-O burning
Si burning
ejection, explosion
condensation
x-process
N=50
r s
NEUTRONS
N=82 N=126
r
s
s
r
p-process
Nuclear reactions:
• energy generation
• nucleosynthesis
alberto.mengoni@cern.ch

Nucleosynthesis beyond Fe
process
conditions
timescale
site
s-process
(n,γ)
β-decay
...
T~ 0.1 GK
τ n ~ 1-1000 yr, n n ~10 7-8 /cm 3
10 2 yr
10 5-6 yrs
Massive stars (weak)
Low-mass AGB stars (main)
r-process
(n,γ)
β-decay
β-delayed n-emission
fission
...
T~1-2 GK
τ n ~ μs, n n ~10 24 /cm 3
< 1s
Type II Supernovae ?
Neutron Star Mergers ?
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The r-process r
path
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The canonical r-process
(n,γ) ↔ (γ,n) time-reversal invariance (detailed balance) leads to:
log
λ
λ
n,
γ
γ , n
≈
log
N n
−
34.07
−
3
2
log
A
T
A + 1
9
+
5.04
T
9
Q(
Z,
A
+ 1)
for example:
λ γ,n ~ λ n,γ for Q n ~ 2 MeV (usual definition of “r-process path”)
under the condition: N n = 10 24 cm -3 and T = T 9
needs masses & β-decay rates of neutron-rich rich nuclei
along the r-process r
path
D D Clayton, “Principle of stellar evolutions and nucleosynthesis”, U of Chicago Press, 1968, pag. 584 (Problem 7-30).

Endpoint of the r-processr
r-process ended
by n-induced n
fission
or spontaneous
fission
(different paths for
different conditions)
Goriely & Clerbaux A&A 348 (1999), 798
Source: H Schatz (MSU)
Consequences:
- modification of the A~130 r-process r
abundance peak
- fission products can be seed for additional r-processing r
up to A~250
fission again
fission recycling

Role of β-delayed n-emissionn
Neutron rich nuclei can emit one or more neutrons during β-decay if S n

Effects:
during r-processr
process: none as neutrons get recaptured quickly
during freezeout: modification of final abundance
late time neutron production (those get recaptured)
Calculated r-process production of elements (Kratz et al. ApJ 403 (1993) 216):
before β-decay
after β-decay
smoothing effect from β-delayed n emission !
Source: H Schatz (MSU)

Example: impact of P n for
for
137 Sb
Cs (55)
Xe (54)
I (53)
Te (52)
Sb (51)
Sn (50)
In (49)
Cd (48)
Ag (47)
Cs131
> 99
Cs132
> 99
Cs133 Cs134
> 99
Cs135 Cs136
19.00
Cs137
> 99
Cs138
> 99
Cs139
> 99
Cs140
63.70
Cs141
24.94
Cs142
1.70
Cs143
1.78
Cs144
1.01
Cs145
0.59
Cs146
0.32
Cs147
0.23
Xe130 Xe131 Xe132 Xe133 Xe134 Xe135 Xe136 Xe137 Xe138 Xe139 Xe140 Xe141 Xe142 Xe143 Xe144 Xe145 Xe146
> 99 > 99 > 99 > 99P n 39.68 =0% 13.60 1.73 1.24 0.30 1.15 0.90
I129 I130
> 99
I131
> 99
I132
> 99
I133
> 99
I134
> 99
I135
> 99
I136
83.40
I137
24.50
I138
6.49
I139
2.28
I140
0.86
I141
0.43
I142 I143 I144 I145
Te128 Te129 Te130 Te131 Te132 Te133 Te134 Te135 Te136 Te137 Te138 Te139 Te140 Te141 Te142 Te143 Te144
> 99 > 99 > 99 > 99 > 99 19.00 17.50 2.49 1.40
Sb127 Sb128 Sb129 Sb130 Sb131 Sb132
PSb133
n =99.9%
Sb134 Sb135 Sb136 Sb137 Sb138 Sb139 Sb140 Sb141 Sb142 Sb143
> 99 > 99 > 99 > 99 > 99 > 99 > 99 1.66 0.82
Sn126
> 99
Sn127
> 99
Sn128
> 99
Sn129
> 99
Sn130
> 99
Sn131
56.00
Sn132
39.70
Sn133
1.20
Sn134
1.12
Sn135 Sn136 Sn137 Sn138 Sn139 Sn140 Sn141 Sn142
In125
2.36
In126
1.60
In127
1.09
In128
0.84
In129
0.61
In130
0.26
In131
0.28
In132
0.20
In133
0.18
In134 In135 In136 In137 In138 In139 In140 In141
Cd124 Cd125 Cd126 Cd127 Cd128 Cd129 Cd130 Cd131 Cd132 Cd133 Cd134 Cd135 Cd136 Cd138 Cd139 Cd140
10 1
1.24 0.65 0.51 0.43 0.34 0.27 0.20
A=136
Ag123 Ag124 Ag125 Ag126 Ag127 Ag128 Ag129 Ag130 Ag131 Ag132 Ag133 Ag135 Ag136 Ag137 Ag138 Ag139
0.29 0.17 0.16 0.10 0.11 0.06 0.05
( 99%)
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92
Source: H Schatz (MSU)
abundance (per 10 6 Si)
10 0
10 -1
10 -2
r-process
r-process
waiting
waiting
point
point
Pn=0%
solar
Pn=99%
A=137
( 0%)
r-process
waiting point
125 130 135 140 145
mass number A

Summary: nuclear physics for the r-processr
S n
, M
T 1/2
P n
fission
G
N A
quantity
neutron separation energy, mass
β-decay half-lives
β-delayed n-emission branchings
branchings and products
partition functions
neutron capture rates
effect
path
abundance pattern
timescale
final abundance pattern
endpoint
abundance pattern?
degree of fission cycling
path (very weakly)
final abundance pattern during freezeout?
conditions for waiting point approximation
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Experimental quests & tools
• Ground-state properties & spectroscopy
masses, β-decay rates, spectra
• Resonance properties
elastic, inelastic scattering
transfer reactions
• Capture reactions
resonant & direct capture
Coulomb dissociation
indirect methods (ANC, THM, etc.)
www.cyc.ucl.ac.be/CARINA
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Main goals of the CARINA (*) network
‣ To carry out mapping studies of the European situation in terms of projects, facilities and
teams in order to identify the available instrumentation and human potential.
‣ To develop the research capabilities of existing Large Scale Facilities (LSF) and of smaller
laboratories and enhance involvement in the future RIB facilities.
‣ To record the needs for new instrumentation and techniques; look for existing “solutions” in
other fields.
‣ To coordinate research efforts by defining and proposing common research goals and by
encouraging new collaborations and new R&D projects.
(*)
CARINA: Challenges and Advanced Research in Nuclear Astrophysics
Date of beginning: 1 January 2005
Date of end: 31 December 2008
Budget: 35 k€
Co-ordinator: Carmen Angulo (CRC, Louvain-la-Neuve)

CARINA Tasks
Task 1: Setup activity
Four working groups have been established (January 2005):
1. "Theory" - nuclear and astrophysical models
Conveners: Alain Coc (CSNSM) / Jordi José (Barcelona)
2. "Instrumentation"
Conveners : Tom Davinson (Edinburgh) / Giacomo de Angelis (INFN LNL)
3. “Link to the EURONS_LSF”
Conveners : Alberto Mengoni (CERN) / Klaus Sümmerer (GSI)
4. “Link to non-EURONS_LSF labs working on nuclear astrophysics”
Conveners : Michael Heil (KFZ Karlsruhe) / Endre Somorjai (ATOMKI)
Task 2: link to EURONS, organization of workshops, website, reports, etc.
www.cyc.ucl.ac.be/CARINA
Source: Carmen Angulo (CARINA)

N-02 CARINA activities in 2006
• Mapping studies of laboratories and experimental groups
(done, see annex to annual report 2005)
– Working group 3 (Klaus Suemmerer / Alberto Mengoni)
– Working group 4 (Michael Heil / Endre Somorjai)
• Mapping studies of theoretical groups
– Working group 1 (Alain Coc / Jordi José)
– Contact of groups working on:
• Astrophysical models (and observations)
• Nuclear theory for astrophysical applications
– Extended list, more than 25 additional groups
• Already positive (and enthusiastic) answers received
www.cyc.ucl.ac.be/CARINA
Source: Carmen Angulo (CARINA)

N-02 CARINA activities in 2006
• Survey of key reactions and instrumentation
– Identification of astrophysical sites
• Explosive burning – 80% done
• AGB’s stars – 50 % done
• s-, p-, and r-process – just started
• Work mainly done by e-mail
• Discussions to take place during “Nuclei in the Cosmos IX”
at CERN, Geneva, June 25-30, 2006
Additional SC meeting by the end of 2006
www.cyc.ucl.ac.be/CARINA
Source: Carmen Angulo (CARINA)

N-02 CARINA activities in 2006
• Workshop on data compilations in Basel (June 23-25)
– Goal:
• Basic need in all astrophysical modeling to have access to the best
available and most consistent input data.
• Bring together (experimental and theoretical) data providers,
experienced experts on an unbiased analysis, and the modelers who are
in urgent need of utilizing the best available data input
– Scientific contribution from CARINA (advisory committee)
– No financial contribution (thanks to JINA!)
Need of involvement on international scientific activities:
collaborative work
www.cyc.ucl.ac.be/CARINA
Source: Carmen Angulo (CARINA)

N-02 CARINA activities in 2006
• EURISOL: subtask « astrophysics »
– Invited talk at the EURISOL meeting in Trento, January 2006.
– Request from EURISOL task 10 leader to coordinate the subtask
“astrophysics”
• Acceptance as this involves the CARINA community: similar interests,
work effectively.
• Meeting at Pisa, April 10-12
All documents produced by CARINA
are available on the website:
www.cyc.ucl.ac.be/CARINA
Source: Carmen Angulo (CARINA)

Instrumentation for nuclear astrophysics
A survey of instrumentation available in present-day laboratories active in
experimental nuclear astrophysics suggests the following required devices:
‣ Gas targets (recirculation for rare gases; continuous luminosity monitoring)
‣ A multi-stage fusion-product recoil separator (high leak-beam suppression, high rate
focal plane detectors)
‣ A high-resolution magnetic forward spectrometer (high rate focal plane detectors)
‣ Large-area, fine-granularity solid-state detectors or telescopes (on sharing basis;
standard electronics and DAQ systems)
‣ A dedicated high-resolution, high-efficiency gamma-ray detection system
The “flagship” ISOL type facility must have these tools
available for the nuclear astrophysics community
www.cyc.ucl.ac.be/CARINA
Source: Carmen Angulo (CARINA)

Some additional key reactions
18
F(p,α) 15 O
The competition between the 18 F(p,α) 15 O and the 18 F β-decay has consequences regarding a
possible observation of the 511 keV γ-ray from novae (ex. INTEGRAL): γ-rays from novae
have not been detected yet.
‣ Several experiments already performed…
17
O(p,γ) 18 F , 17 O(p,α) 14 N
17 O (and perhaps 19 F): galactic chemical evolution; it is believed that 17 O on earth or in our
bodies was made in novae
C, N, O elemental abundances are observed in emission spectra of nova ejecta; isotopic
ratios 12 C/ 13 C and 14 N/ 15 N are observed in pre-solar grains that originated from nova
explosions
‣ Recent experiments at LENA @ NC (Iliadis, Champagne et al.); CSNSM @ Orsay
(Tatischeff et al.)
Source: Carmen Angulo (CARINA)

Some additional key reactions
14
O(α,p) 17 F
The reaction is thought to play an important role in advanced stages of hydrogen burning,
either as: a way of bypassing the slow positron decay of 14 O (t 1/2 = 70.6 s) in the hot CNO cycle
or as a starting point to break out the cycle through the subsequent 17 F(p,γ) 18 Ne(α,p) 21 Na
reactions.
‣ Recent experiment at RIKEN; project at LLN
15
O(α,γ) 19 Ne
One of the main breakout reaction from the hot CNO cycle.
No direct measurement ever performed:
‣ Very low cross section: very intense 15 O beam needed (< 10 12 pps)
‣ Presently, 15 O beam intensity is ~ 10 7 pps.
Source: Carmen Angulo (CARINA)

Some additional key reactions
22
Na(p,γ) 23 Mg
Peak fluxes for the 1275 keV γ-ray line ( 22 Na decay) might be detectable by near future γ-ray
satellites (i.e. INTEGRAL) if an ONe nova explodes within a distance of less than ~ 0.5 kpc.
30
P(p,γ) 31 Si
Nuclear activity in the Si-Ca region is powered by a leakage from the NeNa-MgAl region,
where the activity is confined during the early stages of the outburst. This is the main
reaction that drives nuclear activity towards heavier species beyond S.
‣ Uncertainties affecting 30 P(p,γ) 31 S influence Si yields (relevant for the identification of
presolar nova candidate grains) and the nuclear activity beyond S (J. José, 2004)
Source: Carmen Angulo (CARINA)

The end

Example:
3 He + 3 He → 4 He + 2p
T ~ 15x10 6 K (e.g. our Sun) ⇒ kT ~ 1 keV
E 0 ~ 20 KeV
σ ( E)
=
1
E
e
−2πη
S(
E)

Example:
3 He + 3 He → 4 He + 2p
T ~ 15x10 6 K (e.g. our Sun) ⇒ kT ~ 1 keV
E 0 ~ 20 KeV