0 1 2

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

59

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)

3 reaction++ 12C p process:

14O+ 17F+p17F+p 18Ne18Ne+ …

In detail:p process

Alternating (,p) and (p,) reactions:For each proton capture there is an (,p) reaction releasing a proton

Net effect: pure He burning

Mass known < 10 keV

Mass known > 10 keV

Only half-life known

seen

Measure: decay properties gs masses level properties rates/cross sections

Figure: Schatz&Rehm, Nucl. Phys. A,

Reaction rates:• direct measurements difficult• “indirect” methods:

• Coulomb breakup• (p,p)• transfer reactions stable beams and RIBS

Guide direct measurements Huge reduction in uncertainties If capture on excited states matters only choice

NSCL Set of experimentsuse (p,d) to determinelevel structure

ISOLTRAPRodriguez et al.NSCL Lebit

Bollen et al.

ANL CPTSavard et al.

Recent progress in mass measurements

JYFL Trap

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 rare isotope beam experiments

• -decay half-lives• masses• reaction rates mainly (p,), (,p)

(ok)

(in progress)

(just begun)

Bishop et al. 2003 (TRIUMF)

H. Schatz

1) Direct Measurements

For p-captureonly 2 cases so far !

21Na + p 22Mg

2) First step: indirect techniques with low intensity rare isotope beams

Need RIA

Many developed at a number of facilities: (ANL, GSI, MSU, ORNL, RIKEN, Texas A&M, …)

Example: 32Cl + p 33Ar* 33Ar +

Resonant enhancement through states in 33Ar ?

Techniques with rare isotope beams

-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

NSCL Experiment: Clement et al. PRL 92 (2004) 2502

x10000 uncertainty

shell model only

reac

tion

rate

(cm

3/s

/mol

e)

temperature (GK)

x 3 uncertaintywith experimental data

stellar reaction rate

dPlastic

34Ar

33Arexcited

H. Schatz

Stellar Enhancement Factor

SEF = stellar capture rate

ground state capture rate

this work

NON Smoker

direct measurement of this rate is not possible – need indirect methods SEF’s should be calculated with shell model if possible

1+

2+90 keV

3.364

3.456

3.819

4.190

33Ar

32Cl

5/2+

7/2+

5/2+

1/2+MeV

3.343

Dominantresonance

H. Schatz

Mass ejection in X-ray bursts ? Weinberg, Bildsten, Schatz 2005T

empe

ratu

re (

K)

Column density (g/cm2)

Initial ra

diative profile

wind

?

Winds can eject <1% of accreted massDoes convection zone reach into theouter layers that get blown off ???

Wind ejects ashes in radius expansion bursts for wide range of parameters

surface

Neutron star interior

wind

dept

h

H. Schatz

Reaction flow during burst rise in pure He flash

12C

13N

16O

slow

(p,)

(,p)

12C() bypass

Need protons as catalysts(~109 are enough !)

Source: (,p) reactionsand feedback through bypass

Increases risetime Triggers late reexpansion of convection zone enhances production of heavy elements vs. carbon

H. Schatz

Composition of ejected material

32S28Si

Weak p-captureon initial Fe seed

Observable with current X-ray telescopes

in wind on NS surface

as spectral edges Explanation for enhanced Ne/O ratio in 4U1543-624, 4U1850-087, … ??? (ratios ~1 – ISM 0.18)

Observable with current X-ray telescopes

in wind on NS surface

as spectral edges Explanation for enhanced Ne/O ratio in 4U1543-624, 4U1850-087, … ??? (ratios ~1 – ISM 0.18)

Neutron star surface

ocean

Innercrust

outercrust

H,He

gasashes

~ 20m, =109 g/cm3

superburst

H. Schatz

Step 2: Deep ocean burning: Superbursts

long duration through longer radiation transport long time to accumulate means long recurrence time more material means more total energy by same factor for same MeV/u)

Accreting Neutron Star Surface

fuel

ashesocean

Innercrust

outercrust

H,He

gas

core

Radiation transport

~1 m

~10 m

~100 m

~1 km

10 km

Thermonuclear H+He burning(rp process)

~10s

Deep burning ?

~hours

~ x1000 longer burst duration~ x1000 longer recurrence time~ x1000 more energy

H. Schatz

The origin of superbursts – Ashes to Ashes

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 (Cumming & Bildsten 2001)

(Schatz, Bildsten, Cumming, ApJ Lett. 583(2003)L87

Ashes to ashes – the origin of superbursts ?

Puzzle:The ocean is too cold ignition about every 10 years instead of every year as observed

Energy generation everywhere else in comos:• Stars• X-ray bursts, Novae

Energy generation in Superbursts(plus C->Ni fusion)only place in cosmos ? And nuclear power plants

on earth

Neutron star surface

ocean

Innercrust

outercrust

H,He

gasashes

ashes

~ 25 – 70 m =109-13 g/cm3

H. Schatz

Step 3: Crust burning

Surface of accreting neutron stars

Neutron star surface

Ocean (palladium? Zinc?)

Innercrust

Crust of rare isotopes

gas

D. Page

X-ray bursts

1m

10m

Hydrogen, Helium

ashes

superbursts

34Ne

1.5 x 1012 g/cm3

68Ca

1.8 x 1012 g/cm3

106Ge

56Ar2.5 x 1011 g/cm3

4.8 x 1011 g/cm3

72Ca 4.4 x 1012 g/cm3

rp-ashes

106Pd

56Fe

Haensel & Zdunik 1990, 2003Gupta et al. 2006

Known mass

Crust processes

Known mass

Crust processes

Reach of next generation Rare Isotope Facility FRIB

(here MSU’s ISF concept)(mass measurements)

Reach of next generation Rare Isotope Facility FRIB

(here MSU’s ISF concept)(mass measurements)

Recent massmeasurements

at GSI(Scheidenberger et al.,

Matos et al.)

Recent massmeasurements

at GSI(Scheidenberger et al.,

Matos et al.)

Recent TOF massmeasurements

at MSU(Matos et al.)

Recent TOF massmeasurements

at MSU(Matos et al.)

Recent massmeasurementsat ISOLTRAP(Blaum et. al.)

Recent massmeasurementsat ISOLTRAP(Blaum et. al.)

Q-valuemeasurement

at ORNL(Thomas et al. 2005)

Q-valuemeasurement

at ORNL(Thomas et al. 2005)

Recent massmeasurements

at Jyvaskyla(Hager et. al. 2006)

Recent massmeasurements

at Jyvaskyla(Hager et. al. 2006)

Excitation energyof main transition

NEW JINA Result: S. Gupta, E. Brown, H. Schatz,K.-L. Kratz, P. Moeller 2007

Electron capture into excitedstates increases heatingby up to a factor of ~10

NEW JINA Result: S. Gupta, E. Brown, H. Schatz,K.-L. Kratz, P. Moeller 2007

Electron capture into excitedstates increases heatingby up to a factor of ~10

Increasedheating

superbursts

rp-ashes

Former estimate

New heatingenhanced by x 5-6

Heats entire crust and increases ocean temperature from 480 Mio K to 500 Mio K

Enhanced crust heating

Impact of new crust modeling on superbursts

Can the additional heating from EC into excited states make the crust hot enough to get the superburst ignition depth in line with observations ?

Almost:

Without excited states

Igni

tion

dept

h

Mass number of crust composition (pure single species crust)

Inferred fromobservations

KS 1731-260 (Wijands 2001)

Bright X-ray burster for ~12 yrAccretion shut off early 2001

Is residual luminosity coolingneutron star crust ? If yes: probe neutron star !

H. Schatz

Observables: transients in quiescence

Low crust conductivity, normal core cooling

High crust conductivity, enhanced core cooling

(Ouellette & Brown 2005)(Rutledge 2002)

H. Schatz

Comparison with observations during quiescence

High crust conductivityEnhanced core cooling

Low crust conductivityNormal core cooling

Low crust conductivityEnhanced core cooling

High crust conductivityNormal core cooling

(data from Wijnands 2004)

but: a superburst has been observed from KS 1731-260 this indicates a hotter crust and low crust conductivity

(Brown 2004)

but: a superburst has been observed from KS 1731-260 this indicates a hotter crust and low crust conductivity

(Brown 2004)

M. Ouellette

H. Schatz

Superbursts as probes for NS cooling

Superburst ignition depth (Ed Brown, to be published)(for accretion rate of 3e17 g/s and X(12C)=0.1)

Recurrence time depends on crust conductivity and core cooling Observations require LOW conductivity and no enhanced cooling (incl. KS1731-260)

Recurrence time depends on crust conductivity and core cooling Observations require LOW conductivity and no enhanced cooling (incl. KS1731-260)

“regular” core cooling

“enhanced” core cooling

Low crust conductivity

High crust conductivity

27 yr

5.2 yr

1.4 yr3.1 yr

Recurrence times(observed ~ 1yr)