Nuclear Astrophysics - Nuclear Physics

ns.ph.liv.ac.uk

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

www.cyc.ucl.ac.be/CARINA

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ack to explosions

www.cyc.ucl.ac.be/CARINA

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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 ?

www.cyc.ucl.ac.be/CARINA

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The r-process r

path

www.cyc.ucl.ac.be/CARINA

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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

a mengoni for CARINA


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

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