experiments in nuclear - cnea
TRANSCRIPT
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