Experiments in Nuclear Astrophysics

K. E. Rehm

Argonne National Laboratory

HST (visible)

CGRO/INTEGRAL(γ)

Chandra (X-rays)

WMAP( μ wave)

Spitzer (IR)

GLAST(γ-rays)

NGST (near IR) 1990 2000 2010

Main sequence star

Novae Supernovae Neutron star Population III stars

Big Bang

Neutrino oscillations Synthesis of the Elements

Accelerating universe

Dense Matter Supermassivestars

Cosmology

Dark energy

Selection:

•Variety of astrophysical sites

•Variety of experimental equipment

•Personal prejudice

Outline:

•Neutrinos from the sun

•Novae: Production of 22Na

•X-ray bursts: masses of waiting point nuclei

•Red giant stars: 12C(α,γ)16O

•r-process measurements

(Iguassú 1609)

Reaction paths in nuclear astrophysics

ANL

TAMU

ND

RNB Production Facilities 2005

ORNL

FSU

USP

RIKEN

JAERICIAE

INFN

NSC

TIFR

NSCLISAC GANIL GSI

REX-I

MAFF

Lanzhou

CRIB

EURISOLRIA

DRIBS

SPIRAL

EXCYT

ISOL

Fragment.

In-Flight

LLN

Comparison - Experiments with stable and unstable beams

• High beam intensities• Good beam qualities

(narrow resonances)• Good targets available• Small energy loss of p or α

• Detection efficiency small for (p,γ) and (α,p)

• Beam intensities lower by 3-6 orders of magnitude

• Beam contaminants• Have to use inverse kinematics • Need for gas targets• Higher energy loss of heavy

ions (narrow resonances)• Increased detection efficiency

for inverse kinematics

Stable beams Radioactive beams

p,α 16Ν, 18Νe, 21Νa,..

Neutrinos from the Sun

Precision Measurements with Radioactive Beams?

Homestake Superkamiokande SNO

Neutrino Detectors

Study of the 8B β-spectrum

8B

8Be 2 α

2+2+

β+

ν

PRC36, 298(87)

ν-oscillations

ν’s have mass

Physics beyond the SM

ΔE~ ±100 keV

SiSi

αα

energy lossdead layer

corrections needed for: Eα = 1.5 MeV

Techniques to measure the decay of 8B 8Be 2α

3He beam

6Li

6Li(3He,n)8B (T ½=0.76s) 8Be

6Li

Stop an energetic 8B beam in the middle of a Si detector

8B, 27 MeV

Si detector

90 μ thick

T1/2=0.76s

Beam on 1.5s

Beam off 1.5s

3He gas cell

6Li3+ beam

3He(6Li,8B)n

6Li3+8B5+

In-Flight Production of 8B (T1/2=0.76s)

to experiment

35 MeV

bending magnet

Energy calibration?

Corrections: “Energy summing”

8B (β+ ν) 8Be 2α

β+

Si detectorpositron detector

ΔE ~ 24 ± 3 keV

20Na (β+) 20Ne 16O + α

8B 8Be 2α 20Na 20Ne α + 16O

Experimental Results

Comparison of 8B-decay with α−α scattering

E(2+)[keV]

Γ(2+)[keV]

source

3024±13 1426±32 α + α

3120±130 1700±130 8B decayPRC33,303

3012±7 1382±19 8B decayThis work

E(2+)[keV]

Γ(2+)[keV]

source

3040±300 1500±20 Ajzenb. 1988

3000±100 1230±200 9Be(d,t)

3120±100 1430±60 9Be(d,t)

3060±300 1370±70 “best value” 2002

8B Neutrino spectrum

ANLBahcall et al.

Garcia et al.

γ-ray Astronomy7Be (53 d)18F (110 m)22Na (2.6 y)

26Al (7.2 My)44Ti (60 y)

53Mn (3.7 My)56Co (77 d)

60Fe (1.5 My)

….INTEGRAL

(GLAST, ACT)

Produced in Novae

SNe

Nova V382 1999 VelorumNOVAERed giant - white dwarf

“galactic cannibalism”

•~30/year/galaxy

•duration of days

•E=1036 erg/s (sun 1033 erg/s)

Ne-Na cycle

Mg Ne O V382 Vel

Chandra

COMPTEL Search for 22NaA. Iyudin et al. Astron. Astrophys. 300,422(1995)

Expected from Nova models(S. Starrfield et al. ApJ391, L71(1992))

•Wrong distance?

•Wrong hydrodynamics?

•Wrong reaction rates?

Mcalc(22Na) ~ 1.5x10-7 M

Mobs(22Na) < 3x10-8 M

D=2.3±0.5 kpc

Theoretical estimates for the 21Na(p,γ)22Mg reaction rate: uncertainties up to a factor of 50

For 22Na(p,γ)23Mg the uncertainties are a factor of 100

T9

Rate

M. Wiescher et al., Astron. Astrophys. 160, 56(1986)

J. José et al., ApJ 520, 347(1999)

N. Bateman et al., PRC63, 035803(2001)

J. Hardy et al. PRC9, 2654(1974)

J. Nolen et al. NIM 115, 189(1974)ΔE=212 keV

J. Caggiano et al. PRC66, 015804(2002)

22Mg

Measurement of 21Na(p,γ)22Mg at TRIUMF

p(21Na,22Mg)γ, T1/2(21Na)=22.5 s

DRAGON

D. Hutcheon et al. NIM A498,190 (2003)

New experimental uncertainty

21Na(p,γ)22Mg

Rate

T9

Spectrum of 23Mg [22Na(p,γ)23Mg]

7579 keV

•need good energy resolution

•need spin values

•need gamma widths

use Gammasphere

Gamma Sphere

γγωγ Γ

+++

≈Γ

ΓΓ

+++

=)12)(12(

)12()12)(12(

)12(

2121 jjJ

jjJ p

22Na(p,γ)23Mg studied via 12C(12C,n)23Mg at Gammasphere

Resonance strength

23Mg sum of 450+1600+2263 keV gates

Limits of detectability with INTEGRAL

Theoretical estimates

New 21Na(p,γ) rate

New 22Na(p,γ) rate

1kpc (Integral)

22Na uncertainties considerably reduced

sun

Sensitivity of γ-ray Satellites

Integral GLAST

Reactions on the surface of a neutron star

Mass: ~1.4 M

Radius: ~10 km

Density: ~1014 g/cm

X-ray bursts

T (sec)

triple α reaction

(α,p),(p,γ) reactions

(p,γ) reactions

H. Schatz et al. Phys. Rep. 294,167(1998)

waiting point

T½ =35.5 s

The 68Se Waiting Point

Need masses of 68Se and 69Br

(particle unstable)

Sensitivity of X-ray luminosity to masses of several waiting points (60Zn,64Ge,68Se,72Kr)

B. A. Brown et al.

Phys. Rev. C65, 045802 (2002)

Δm ~ 10 keV

CPT at ATLAS

Mass measurement with Penning traps

64Ge 68Se

CPT: J. A. Clark et al. (PRL2004) ME=-54232±19 keVND/ANL: A. Wöhr et al. (NPA2004), ME=-54189±240

Mass of 69Br needs to be extrapolated:

Future possibilities at RIA: 68Se(3He,d)69Br70Br(d,t)69Br70Kr(d,3He)69Br

Audi-Wapstra: ME=-54150 ± 300 keV

GANIL: A. S. Lalleman, Hyperf. Int.132,315(2001) ME=-52347 ± 80 keV

GANIL: G. F. Lima et al. PRC 65,044618(2002) ME=-53620 ± 1000 keV

Summary of Mass Measurements:

•Masses of most critical rp-waiting point nuclei measured

•Many reaction rates still unknown

100

10

1

10-1

10-2

10-3

T1/2

[s]

Audi-Wapstra

GANIL

The 12C(α,γ)16O Reaction

The determination of the ratio 12C/16O produced in helium burning is a problem of paramount importance in Nuclear Astrophysics.

W. Fowler, Nobel prize lecture 1982

Universe Human Body

Hydrogen 73%

Helium 25%

Oxygen 1%

Other 1%

Oxygen 61%

Carbon 23%

Hydrogen 10%Nitrogen 2.6%Calcium 1.4%Phosphorus 1.1%

Other 0.9%

Relative Abundance by Weight

Level structure of 16O

σ ~10-17 b !pres. exp. limit ~ 10-11 b

Need indirect techniques:

•16N beta-delayed α decay

•12C(α,α) scattering

S(E)

•High intensity 16N beam

•Detector with no β sensitivity

S(E1) from the β-delayed α decay of 16N16N(β)16O 12C+α

β-delayed α decay of 16N 16O

Eα

Interference with sub-threshold state

J. Humblet et al., Phys. Rev. C44, 2530(1991)

16N β decay

direct (α,γ) measurements at higher energies12C + α elastic scattering phase shifts

Sensitivity of S(E1) to different experiments(R. Azuma et al., Phys. Rev. C50, 1194(1994)

310:1

620:1

310:1

SinglesCoincid.Singles

620:1

17,18N subtracted

TRIUMF 93 (PRC 50, 1194(1994)

Rotating wheel/cathode

4 Ionization chambers

16N beam

T ½=7.1 s

Stepping motor, encoder

Experimental setup for the study of the β-delayed α decay of 16N

(4 high-acceptance gas ionization chambers, practically insensitive to β’s

Rotating wheel, cathode

d(15N,16N)p

D2

15N

~ 100 pnA

16N , I ~ 3x106/s

Radioactive Beam Production

Particle identification

16N7+

15N6,7+

16O7+

20Ne8+

range

E2

22o bending magnet

experimental data detector simulation

16N 16O 12C + α

1 2

Preliminary +

+ incomplete stopping

rapid neutron capture

r-process studies

r process (in SNe)

1987A

Needed: •Masses

•T1/2

•(n,γ) rates

SNe indicators on Earth

60Fe T1/2=1.5 My (AMS techniques)K. Knie et al.

Phys. Rev. Lett. 83, 18(1999)

Phys. Rev. Lettt. 93, 171103 (2004).

182Hf T1/2=9 MyC. Vockenhuber et al.,

New Astr. Rev. 48, 161(2004)

244Pu T1/2=81 MyM. Paul et al. ApJ, 558, L133(2001)

Long-lived radioisotopes

e.g. 60Fe

Abundance of the elements

Stable nuclidesNuclides with previously known masses

Known nuclides

Measured nuclides with unknownmasses before (80)Measured nuclides with previously known masses

Neutron Number

Proton Number

2028

50

82

8

8

20

28

50

82

126

r-process

r-process

Abundances of Elements in Universe

C. Scheidenberger et al. To be publ.

Mass measurements at the GSI storage ring

Fission fragments from 252Cf are difficult to obtain by other methods.

-3 -2 -1 0 1 2 355

60

65

70

75

80

149Ce2+

(TO

F in

mic

rose

cond

s) /

2

Frequency applied - 1214469.23 Hz-3 -2 -1 0 1 2 3

60

65

70

75

80

85

149Pr2+

(TO

F in

mic

rose

cond

s) /

2

Frequency applied - 1214508.01 Hz

ANL CPT group, to be published

Measurements on neutron-rich nuclei

Yväskylä, prelim.

J. Clark, to be publ.

limits of known nuclei

130Cd, 129Ag [CERN] (PRL91, 162503(03))78Ni [MSU] PRL 94, 112501(05)

Difficult experiments:

Need a next generation facility

Summary:Advances in

Observational astronomy

Multi-dimensional computer simulations

Nuclear data (cross sections, masses, half-lives..)

Significant reductions in uncertainties for quiescent burning, e.g. 3He(4He,γ), 7Be(p,γ),14N(p,γ),12C(α,γ)..).

New experimental data for explosive stellar nucleo-synthesis, e.g. 21Na(p,γ) [novae], 68Se [X-ray bursts] from radioactive beams.

‘Extreme’ environments (e.g. supernovae) need a next generation facility.

Dark blue:something known(at least a half-life)

Extremely neutron richnuclei in r-process path

Red: Within reach at RIA80% of r-process path up to mass 208

Stable nuclei

Number of neutrons

Num

ber o

f pro

tons

topics of this talk

rp process

The Future with RIA

Improvement with RIA:16N x105

21Na x102

22Na x103

68Se x105

8B x106

Summary

Recent measurements on n-rich isotopes

26 neutron-rich isotopes measured up to now

-600

-400

-200

0

200

400

600

800

140 142 144 146 148 150 152 154

A (amu)

Mea

sure

d-Ta

bula

ted*

mas

s (m

u)

BaLaCePr

No eglu and egld windows

With eglu and egld gates

( )θcos~ RDEVG −⋅A

G

CR θ

D

⎟⎟⎠

⎞⎜⎜⎝

⎛−⋅ θλ cos1~ 2

2

mZEEV G

For 10B(n,α)7LiEα=1.5 MeV, random θ

ELi=4/7*Eα

E

random Eα, random θ

ELi=4/7*Eα

E

VG VG

X-ray bursts supernovaenovae

solar reactions

Main sequence star T6 ~ 15, M ~1, t ~ 1010 y

White dwarf star T9 ~ 0.1-0.4, M ~1, t ~ days

Neutron star T9 ~ 0.7-2, M ~1, t ~ 10 sec

massive star T9 ~ 1, M ~10, t ~ sec

T9 ~ 0.1, M ~102-105

t < 106 y

Red Giant star; T9 ~ 0.1 –0.2 , M ~1, t ~ 109 y

supermassive starsred giants

p=160 Torr

p=120 Torr

p=80 Torr

p=60 Torr

AG

C

G

A

7Li α

Pressure dependence

12C(α,γ)16O

S(E1) [keVb]S(E1) [keVb]

PRL 86, 3244(2001)

PRL 88, 072501(2002)

S(E2) [keVb]

NZ

E/A

Mev/u © S. C. Pieper

NZ

E/A

Mev/u© S. C. Pieper

Production reaction: d(15N,16N)p

16N7+

16O7+

15N7+

15N6+

20Ne8+

S factor

Gamowwindow

Input:

S(E1): 16N β decay

S(E2)/S(E1): direct meas. at higher energies

Φ : 12C + α phase shifts

Stotal=S(E1)*f(S(E2)/S(E1),Φ)C. Brune, Phys. Rev. C64,055803(2001)

anode grid

wheel

anode grid

wheel