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JINA Froniters Workshop August 21 st 2005 Searching for Isomers along the rp-Process Path Andreas Wöhr Institute for Nuclear Structure and Astrophysics.

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Presentation on theme: "JINA Froniters Workshop August 21 st 2005 Searching for Isomers along the rp-Process Path Andreas Wöhr Institute for Nuclear Structure and Astrophysics."— Presentation transcript:

1 JINA Froniters Workshop August 21 st 2005 Searching for Isomers along the rp-Process Path Andreas Wöhr Institute for Nuclear Structure and Astrophysics University of Notre Dame

2 JINA Froniters Workshop August 21 st 2005 About the rp-Process The site of the rp-process are most likely X-ray binaries. There –the full rp-process can run –but is unlikely to contribute to nucleosynthesis Experimental information is available form X-ray astronomy. Model calculations can be performed. However, lots of nuclear physics input is needed: ♣ Masses  reaction Q-values ♣nuclear level densities ♣  + -decay half-lives etc...

3 JINA Froniters Workshop August 21 st 2005 X-ray flux Time [s] 0 200

4 JINA Froniters Workshop August 21 st The waiting points can be easily seen from the abundance movie -Slow reactions: -extended energy production -abundance accumulation (steady flow approximation Y=const or Y ~ 1/ ) Waiting Point

5 JINA Froniters Workshop August 21 st 2005

6 72 Br 68 Se 67 As 68 As 70 Kr 69 Br 69 Se 71 Kr 70 Br 71 Br 72 Kr 73 Rb 74 Rb 73 Kr 67 As+p 68 Se+p 69 Br+p 70 Kr 68 As  exp(Q/kT)* Detailed View at Waiting-Point

7 JINA Froniters Workshop August 21 st 2005

8 Experiments Performed 68 Se: 58 Ni( 12 C,2n) MeV –we have seen, the  + -decay products of 68 Se and 68 As –there is some evidence, that we see states in 68 Se 64 Ge: 54 Fe( 12 C,2n) MeV –in an experiment finished last Monday morning, we have evidence, that we have seen the  + -decay- products of 64 Ge and 65 Ge as well as the other reaction channels. –the yield of 64 Ge is about 1% of the total yield. –it has to be determined if we have seen states in 64 Ge with sufficient statistics.

9 JINA Froniters Workshop August 21 st 2005 The Experimental Setup at ND beam

10 JINA Froniters Workshop August 21 st 2005 The Situation in 64 Ge predictetd 0 + State not yet seen! (Y. Sun 2005) „kind of“ similar situation to 68 Se E(0) transition will not be seen in this experiment ! if there the isomers lies not above the 2 + level. Conversion electron spectroscopy needs to be performed 0+0+ E(0)

11 JINA Froniters Workshop August 21 st 2005 Preliminary Data from Recent Experiment Gate on 511 keV line neutron  coincidences 2neutron  coincidences

12 JINA Froniters Workshop August 21 st 2005 Total Projection of  -Coincidences

13 JINA Froniters Workshop August 21 st 2005 Preliminary Conclusion(s) A lot of things have to be done to find these isomers. In the presented case the technique with neutron-gamma coincidences has worked to select the neutron reaction channels. If there is no evidence for a delayed  -transition to the 902 keV state in 64 Ge a conversion electron spectrometer has to be used.

14 JINA Froniters Workshop August 21 st 2005 The Student on the Project: Timo Griesel (Universities of Mainz and Notre Dame) Producer: Ani Aprahamian (University of Notre Dame and JINA) Co-Producer: A.W. The Crew and Tandem Operators: Plamen Boutachkov (University of Notre Dame) Sergio Almaraz-Calderon (University of Notre Dame) Beverly Lau (Reed College, REU student at Notre Dame) Matthew Quinn (University of Notre Dame) Boris Skoromudov (University of Notre Dame) Theory Support: Yang Sun (University of Notre Dame) Targets: John Greene (Argonne National Laboratory) Spiritual Support: Kim Lister (Argonne National Laboratory) Karl-Ludwig Kratz (University of Mainz) Sponsors: University of Notre Dame National Science Foundation Joint Institute of Nuclear Astrophysics (JINA) Johannes Gutenberg Universität Mainz Vistars The End


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