Nuclear Astrophysics with fastradioactive beams
Hendrik SchatzMichigan State University
National Superconducting Cyclotron LaboratoryJoint Institute for Nuclear Astrophysics JINA
Outline:• rp-process• r-process
Neutron star(H and He burninto heavier elements)
Companion star(H + He envelope)
Accretion disk(H and He fallonto neutron star)
Accreting neutron stars
X-ray bursts
Superbursts
Bursts and other nuclear processes
probe M,R, cooling dense matter EOS, superfluidity,
meson condensates, quark matter
strange matter
97-98
2000
Precision X-ray observations(NASA’s RXTE)
Need much more precise nuclear data to make full use of high quality observational data
Galloway et al. 2003
Woosley et al. 2003 astro/ph 0307425
Uncertain models due to nuclear physics
Burst models withdifferent nuclear physicsassumptions
Burst models withdifferent nuclear physicsassumptions
GS 1826-24 burst shape changes ! (Galloway 2003 astro/ph 0308122)
Reality check: Burst comparison with observations
Nuclear physics needed for rp-process:
0 12
3 45 6
7 8
9 10
11 12 13
14
15 16
17 18 19 20
21 22
23 24
25 26 27 28
29 30
31 32
33 34 35 36
37 38 39 4041
42 43 44
45 46 47 48
49 5051 52
5354 55
56
57 58
n (0) H (1)
H e (2)L i (3)
Be (4) B (5) C (6) N (7)
O (8) F (9)
N e (10)N a (11)
M g (12)A l (13)S i (14) P (15)
S (16)C l (17)
A r (18) K (19)
C a (20)Sc (21)
Ti (22) V (23)
C r (24)M n (25)
Fe (26)C o (27)
N i (28)C u (29)
Zn (30)G a (31)
G e (32)As (33)
Se (34)B r (35)K r (36)R b (37)
S r (38) Y (39)
Zr (40)N b (41)
M o (42)Tc (43)
R u (44)R h (45)Pd (46)Ag (47)
C d (48)In (49)
Sn (50)Sb (51)
Te (52) I (53)
Xe (54)
some experimental information available(most rates are still uncertain)
Theoretical reaction rate predictions difficult neardrip line as single resonances dominate rate:
Hauser-Feshbach: not applicable
Shell model: available up to A~63 but large uncertainties (often x1000 - x10000)
(Herndl et al. 1995, Fisker et al. 2001)
Need radioactive beam experiments
• -decay half-lives• masses• reaction rates mainly (p,), (,p)
(ok – but corrections needed)
(in progress)
(just begun)
(various methods, ISOL and fast beams)
33Ar
32Cl + p
Shell model calculation:
3.56 MeV 7/2+
3.97 MeV 5/2+
Ground state
Dominate ratein rp-process
H. Schatz
New experimental techniques at NSCL applied to 32Cl(p,g)33Ar
Herndl et al. 1995
gs 1+
2+89.9 keV
(~ 2.6 MeV)
(1.359 MeV)
predicted level
experimentally known level
Experimental Goal:Measure excitation energies of the relevant states
Focal plane:identify 33Ar
S800 Spectrometer at NSCL:
Plastictarget
Radioactive 34Ar beam84 MeV/u T1/2=844 ms(from 150 MeV/u 36Ar)
33Ar
34Ar
SEGAGe array(14 Detectors)
Beamblocker
H. Schatz
Setup for 34Ar(p,d)33Ar measurement
34Ar
34Ar(p,d)33Ar*
x10000 uncertainty
shell model only
-rays from predicted 3.97 MeV state
Doppler corrected -rays in coincidence with 33Ar in S800 focal plane:
33Ar level energies measured:
3819(4) keV (150 keV below SM)3456(6) keV (104 keV below SM)
33Ar level energies measured:
3819(4) keV (150 keV below SM)3456(6) keV (104 keV below SM)
H. Schatz
reac
tion
rate
(cm
3/s
/mol
e)
temperature (GK)
x 3 uncertaintywith experimental data
stellar reaction rate
New 32Cl(p,)33Ar rate – Clement et al. PRL 92 (2004) 2502
Typical X-ray burst temperatures
0 24
68
10 12
14
16 18
20 2224
26 2830
32
3436
3840
42
4446
48
50 52
5456
5860
6264 66
68
70
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
Tim e:Tem perature:
1.041e-04 s0.850 G K
0 24
68
10 12
14
16 18
20 2224
26 2830
32
3436
3840
42
4446
48
50 52
5456
5860
6264 66
68
70
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
Tim e:Tem perature:
1.076e+03 s6.607 G K
Burst peak (~7 GK)
~ 45% Energy
~ 55% Energy
Carbon can explodedeep in ocean/crust(but need x10 enhancement)(Cumming & Bildsten 2001)
(Schatz, Bildsten, Cumming, ApJ Lett. 583(2003)L87crust made of Fe/Ni ?
Heavy nuclei in rp-ashes
• Disintegration can be main source of energy !• Increased opacity leads to correct ignition depth
H. Schatz
Ashes to ashes – the origin of superbursts ?
r (apid neutron capture) process
Supernovae ? n driven wind ? prompt explosions of ONeMg core ? jets ? explosive He burning ?
What is the origin of about half of elements > Fe(including Gold, Platinum, Silver, Uranium)
Neutron star mergers ?
graph by J. Cowan
H. Schatz
The r(apid neutron capture) process)
Abundance Observations
Nuclear Physics + Abundance Observations
only direct experimental constraint on r-process itself
Nuclear Physics
Pt
Xe
78Ni, 79Cu first bottle necks in n-capture flow (80Zn later)
79Cu: half-life measured 188 ms (Kratz et al, 1991) 78Ni : half-life predicted 130 – 480 ms 3 events @ GSI (Bernas et al. 1997)
Ni
H. Schatz
Some recent r-process motivated experiments
GSI (in-flight fission)Half-lives, Pn values(Schatz, Santi, Stolz et al.)
ISOLDE (ISOL)Decay spectroscopy(Dillmann, Kratz et al. 2003)
GSI (in-flight fission)Masses (IMS)(Matos & Scheidenberger et al.)
GANIL (fragmentation)Decay spectroscopy, Sorlin et al.
ANL/CPT (Cf source) (Clark & Savard et al.)
Remeasured masses with high precision
ORNL (ISOL)(d,p) and Coulex
MSU/NSCL (fragmentation) Half-lives, Pn values
“Fast beam experiments”
NSCL Neutron detector NERO
R-process Beam Si Stack
neutron
3He + n -> t + p
Measure:
• -decay half-lives• Branchings for -delayed n-emission
Measure:
• -decay half-lives• Branchings for -delayed n-emission
Detect:• Particle type (TOF, dE, p)• Implantation time and location• -emission time and location• Neutron- coincidences
Detect:• Particle type (TOF, dE, p)• Implantation time and location• -emission time and location• Neutron- coincidences
H. Schatz
First experiment: r-process in the Ni region (Hosmer et al.)
~ 100 MeV/u
Ene
rgy
loss
in S
i ~ Z
r-process nuclei
Time of flight ~ m/q
Particle Identification:
time (ms)
Total 78Ni yield:11 events in 104 h
77Ni78Ni
75Co 74Co 73Co
0.01
0.1
1
10
71 72 73 74 75 76 77 78 79
This work
Moller 97 (FRDM+QRPA)
Borzov 97(ETFSI+cQRPA)
Moller 03(FRDM+QRPA+ff)
Moller (ETFSI-Q+QRPA+ff)
Borzov03 (QRPA GT+ff)
Nubase 03
P. Hosmer
H. Schatz
Preliminary results
78Ni half-life(11 events)
Hal
f-lif
e (s
)
Mass number
Ni half-lives as a function of mass number – comparison with “global” models
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
70 120 170 220
Mass (A)
Ab
un
da
nc
e (
A.U
.)Observed Solar Abundances
Model Calculation: Half-Lives fromMoeller, et al. 97
Series4
H. Schatz
Impact of 78Ni half-life on r-process models
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
70 120 170 220
Mass (A)
Ab
un
da
nc
e (
A.U
.)Observed Solar Abundances
Model Calculation: Half-Lives fromMoeller, et al. 97
Same but with present 78Ni Result
need to readjust r-process model parameters
Known half-life
NSCLcovers large fraction of A<130 r-process• big discrepancies among r-process models• possibility of multiple r-processes
First NSCL experimentscompletedFirst NSCL experimentscompleted
H. Schatz
NSCL and future facilities reach
Rare Isotope Accelerator (RIA)
Experimental Nuclear Physics + Observations Experimental test of r-process models is within reach Vision: r-process as precision probe
Experimental Nuclear Physics + Observations Experimental test of r-process models is within reach Vision: r-process as precision probe
H. Schatz
Conclusions
Interesting time in Nuclear Astrophysics where observations and experiments zoom in on most extreme (but common) scenarios
Need a complementary approach to nuclear astrophysics• need a variety of experiment types for a wide range of data• need a variety of facilities (ISOL and fragmentation beams, and stable beams too !)• need experiment and nuclear theory to:
• fill in gaps• correct for astrophysical environment• understand nuclear physics
A range of nuclei in the r- and rp-process are now accessible at the NSCL Coupled Cyclotron Facility.
Need a next generation radioactive beam facilities such as RIA or FAIRto address most of the nuclear physics relevant for astrophysics.
Fundamental questions to be answered: The origin of the elements Properties of matter under extreme conditions.
Collaboration
Collaboration
MSU:P. HosmerF. MontesR.R.C. ClementA. EstradeS. LiddickP.F. ManticaC. MortonW.F. MuellerM. OuelletteE. PellegriniP. SantiH. SchatzM. SteinerA. StolzB.E. Tomlin
Mainz:O. ArndtK.-L. KratzB. Pfeiffer
Notre Dame:A. AprahamianA. Woehr
Maryland:W.B. Walters
PNNLP. Reeder
H. Schatz
Collaborations
MSU:
R.R.C. ClementD. BazinW. BenensonB.A. BrownA.L. ColeM.W. CooperA. EstradeM.A. FamianoN.H. FrankA. GadeT. GlasmacherP.T. HosmerW.G. LynchF. MontesW.F. MuellerP. SantiH. SchatzB.M. SherrillM.-J. van GoethemM.S. Wallace
Hope College
P.A. DeYoungG.F. Peaslee
r-process rp-process