28. November 2005 Fission product yield measurements with JYFLTRAP A novel application of a Penning trap H. Penttilä, J. Äystö, V.-V. Elomaa, T. Eronen, U. Hager, J. Hakala, A. Jokinen, A. Kankainen, P. Karvonen, T. Kessler, I. Moore, A. Nieminen, S. Rinta-Antila, T. Sonoda and the IGISOL group Department of Physics, University of Jyväskylä, Finland V. Rubchenya Khlopin Radium Institute, St. Petersburg, Russia M. Valentina Ricciardi, S. Lukic, A.Kelic, K-H. Schmidt GSI, Darmstadt, Germany

28. November 2005 Fission product yield measurements with JYFLTRAP Why fission yield measurement? General curiosity Learning about the fission process Information for needs of RNB facilities and nuclear waste transmutation studies Experimental independend yields necessary for theoretical model developing Low energy particle induced fission yields in context of EURISOL: Fission from secondary low energy protons and neutrons ￫ have to be included for realistic yield estimation

28. November 2005 Fission product yield measurements with JYFLTRAP Why fission yield measurement with the IGISOL? Ion guide is not chemically selective IG produces beams of primary reaction products IG is fast Ions from IG predominantly 1+ A number of fission yield/cross section studies have been performed using ion guide: –M. Leino et al, Phys Rev. C 44, 336 (1991) –P. P. Jauho et al, Phys. Rev. C 49, 2036 (1994) –H. Kudo et al, Phys. Rev. C 57, 178 (1998) –L. Stroe et al, Eur. Phys. J. A 17, 57 (2003) Target 500 V10 kV30 kV Skimmer Beam

28. November 2005 Fission product yield measurements with JYFLTRAP And why with a Penning trap? Counting ions instead of waiting for their decay gives a superior efficiency – compare to relativistic fission (GSI) and unstopped fission fragment measurements (eg. Lohengrin) High mass resolving power of a Penning trap provides unambiguous identification of ions - also the stable and long-lived ones!

28. November 2005 Fission product yield measurements with JYFLTRAP Fission yields measurement: reaction 1)p-induced fission Thin target Stopping ions in helium, guiding to separator Continuous ion stream

28. November 2005 Fission product yield measurements with JYFLTRAP Fission yields measurement: isobar selection 2) Selecting A with a dipole magnet m/q selection mass resolving power 300 Still continuous beam 3) Guiding ions to radiofrequency (RFQ) cooler trap Electrostatic deflector 7 mm entrance slit 4) Collecting ions to RFQ cooler trap Creating bunch Adjusting ion rate 5) Shooting ions from cooler to trap

28. November 2005 Fission product yield measurements with JYFLTRAP Mass selective purification and ion counting TOF MCP 2nd MCP 7) Detecting ions with multichannel plate (MCP) detector high sensitivity 6) Trapping and mass selective manipulation of the ions MRP up to in purification trap Short cycle used to avoid decay losses Typical cycle 300 ms ￫MRP ~ From RFQ

28. November 2005 Fission product yield measurements with JYFLTRAP Determining the relative ion rate For Zirconium isotopes: 101 Zr rate (ions/second) measured Other isotope rate measured Ion rates corrected for decay losses Ratio gives the relative yield

28. November 2005 Fission product yield measurements with JYFLTRAP Zr isotopes yield in fission Maximum relative yield normalised to one Blue line: theoretical model in V.A. Rubchenya, eurisol/Yields-of-n-rich- nuclei.pdf

28. November 2005 Fission product yield measurements with JYFLTRAP Mo and Ge yields in fission

28. November 2005 Fission product yield measurements with JYFLTRAP Sn isotopes yield in fission

28. November 2005 Fission product yield measurements with JYFLTRAP Summary A novel method utilizing a Penning trap to determine the relative, independent, isotopic fission yields was successfully tested for 25 MeV proton induced fission of 238 U at the JYFLTRAP. Relative independent yields for isotopes of 10 elements were measured in a 3 days beam time. Key elements of method: IGISOL separates any element in milliseconds High mass resolving power of the Penning trap gives unambiguous identification of ions Counting ions after trap with MCP gives ultimate sensitivity.