# Presentation: 261747

## Nuclear Astrophysics with fastradioactive beams

**Nuclear Astrophysics with fast****radioactive beams**

**Hendrik Schatz****Michigan State University**
**National Superconducting Cyclotron Laboratory**
**Joint Institute for Nuclear Astrophysics JINA**

**Outline:**
**rp-process**
**r-process**

## Accreting neutron stars

**Neutron star****(H and He burn****into heavier elements)**

**Companion star****(H + He envelope****)**

**Accretion disk****(H and He fall****onto neutron star)**

**Accreting neutron stars**

**X-ray ****bursts**

**Superbursts**

**Notes:**
Explain NS

## Slide 3

**Notes:**
Say something about crust comp

## Precision X-ray observations(NASA’s RXTE)

**Precision X-ray observations**(NASA’s RXTE)

-  GS 1826-24 burst shape changes !     (Galloway 2003 astro/ph 0308122)

**Reality check: Burst comparison with observations**

**Notes:**
Not talking about understanding every little detail, but about taking observations and making full use of them
SHWN THAT THERE IS LINK BETWEEN observation and nuclear physics – nuclear physics not good enough
Slight increase in accretion rate observed

## Nuclear physics needed for rp-process:

- _Nuclear physics needed for rp-process:_

- some experimental
- information available(most rates are still uncertain)

- _Theoretical reaction rate predictions difficult near__drip 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)

## (~ 2.6 MeV)

- 32Cl + p

_**Shell model calculation:**_

**3.56 MeV 7/2****+**

**3.97 MeV 5/2****+**

**Ground state**

**Dominate rate****in rp-process**

- New experimental techniques at NSCL applied to 32Cl(p,g)33Ar

- Herndl et al. 1995

- gs 1+

******(~ 2.6 MeV)**

******(1.359 MeV)**

- predicted level

- experimentally known level

_**Experimental Goal:**_
- Measure excitation energies of the relevant states

## 34Ar(p,d)33Ar*

- Focal plane:identify 33Ar

- S800 Spectrometer at NSCL:

- Plastictarget

- Radioactive 34Ar beam84 MeV/u T1/2=844 ms(from 150 MeV/u 36Ar)

**33****Ar**

**34****Ar**

- SEGAGe array(14 Detectors)

- Beamblocker

**Setup for 34Ar(p,d)33Ar measurement**

**34****Ar**

- 34Ar(p,d)33Ar*

## New 32Cl(p,)33Ar rate – Clement et al. PRL 92 (2004) 2502 

- -rays from predicted 3.97 MeV state

- Doppler corrected -rays in coincidence with 33Ar in S800 focal plane:

- _33__Ar level energies measured:_
- 3819(4) keV  (150 keV below SM)
- 3456(6) keV  (104 keV below SM)

- reaction rate (cm3/s/mole)

- temperature (GK)

- stellar reaction rate

- New 32Cl(p,)33Ar rate – Clement et al. PRL 92 (2004) 2502

- Typical X-ray burst temperatures

## Ashes to ashes – the origin of superbursts ?

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

**Notes:**
Say: Key problem origin of C, problems to make it, peoblems to make it survive, BUT models also do not match observationsNeed: theoretical work and right nuclear physics !  Superbursts ok, key is rp-process during normal bursts

## r (apid neutron capture) process

- <date/time>

**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

**Pt**

**Xe**

**Ni**

**Notes:**
What is the nuclear physics
SAY: equilibrium process, then freezeout
Need wide range of nuclei (broad path) all the way to near the drip line

## Some recent r-process motivated experiments

**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”

**Notes:**
Go next step: NSCL, first experiments

## Measure:

**NSCL Neutron detector NERO**

**R-process Beam**

**Si Stack**

**neutron**

- 3He + n -> t + p

- _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

**First experiment: r-process in the Ni region (Hosmer et al.)**

**~ 100 MeV/u**

**Notes:**
Difficult experiment

## Energy loss in Si ~ Z

- Time of flight ~ m/q

- Particle Identification:

## P. Hosmer

**Preliminary results**

**78Ni half-life****(11 events)**

- Half-life (s)

- Mass number

- Ni half-lives as a function of mass number – comparison with “global” models

**Notes:**
Preliminary
78Ni half-life 11 events
Compare with models: older models DASHED freqently used in r-proces calcs: quite off, except for old Kratz89
Newer versions of same model do better
Look at Moeller – FRDM, shell quenched ETFI-Q remarkably good !!! Role of masses !!! Leave the interpretation to you ...
Argue about physics of these models and need good microscopic models to understand physics BUTfor r-process need GLOABAL model that happens to make good predictions for whatever reason ... Moeller not so bad !!!

## Impact of 78Ni half-life on r-process models

**Impact of ****78****Ni half-life on r-process models**

-  need to readjust r-process model parameters

## NSCL and future facilities reach

**NSCL and future facilities reach**

**Experimental Nuclear Physics + Observations******** Experimental test of r-process models****     is within reach******** Vision: r-process as precision probe**

**Notes:**
Into light r-process
FIRST EXPERIMENT IN NI REGION

##  Collaboration

- 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

## r-process

_**MSU:**_
**P. Hosmer**
**F. Montes**
**R.R.C. Clement**
**A. Estrade**
**S. Liddick**
**P.F. Mantica**
**C. Morton**
**W.F. Mueller**
**M. Ouellette**
**E. Pellegrini**
**P. Santi**
**H. Schatz**
**M. Steiner**
**A. Stolz**
**B.E. Tomlin**

_**Mainz:**_
**O. Arndt**
**K.-L. Kratz**
**B. Pfeiffer**

_**Notre Dame:**_
**A. Aprahamian**
**A. Woehr**

_**Maryland:**_
**W.B. Walters**

_**PNNL**_
**P. Reeder**

**Collaborations**

_**MSU:**_
**R.R.C. Clement**
**D. Bazin**
**W. Benenson**
**B.A. Brown**
**A.L. Cole**
**M.W. Cooper**
**A. Estrade**
**M.A. Famiano**
**N.H. Frank**
**A. Gade**
**T. Glasmacher**
**P.T. Hosmer**
**W.G. Lynch**
**F. Montes**
**W.F. Mueller**
**P. Santi**
**H. Schatz**
**B.M. Sherrill**
**M.-J. van Goethem**
**M.S. Wallace**

_**Hope College**_
**P.A. DeYoung**
**G.F. Peaslee**

- rp-process