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