FISSION YIELD MEASUREMENTS WITH JYFLTRAP

Transcription

1 FISSION YIELD MEASUREMENTS WITH JYFLTRAP Heikki Penttilä The IGISOL group University of Jyväskylä, Finland

2 Quick orientation Jyväskylä JYFLTRAP JYFL accelerator laboratory Me Spectrscopy line IGISOL-4 mass separator facility

3 The IGISOL-4 facility at JYFL IGISOL: Ion Guide Isotope Separator On-Line: a mass separator facility based on ion guide technique, capable making ion beams of any element IGISOL-1: c.a at MC2 proton cyclotron IGISOL-2 ( ) and IGISOL-3 (23 21) at K-13 IGISOL-4 moved/build next to new MCC3 light ion cyclotronin an extension experimental hall in (still coupled to K-13). Commissioning Facility can provide ultra pure beams of fission products Target SPIG Extractor electrode Fission yield (p-induced): 14 atoms/(mc * mbarn) Beam Al block Proton beam 3 MeV, 1 μa 9 Be target Cooling water

4 Fission ion guide technique Based on survival of primary ions from nuclear reaction in helium buffer gas Fast extraction of ions is required to prevent neutralisation Charge state concentration: (), +1, (+2) Produces ions of any element All elements can be studied All ions come directly from fission Ion rate in the formed beam corresponds to the independent fission yield Target Extractor SPIG electrode Beam

5 Fission ion guide technique Based on survival of primary ions from nuclear reaction in helium buffer gas Fast extraction of ions is required to prevent neutralisation Charge state concentration: (), +1, (+2) Produces ions of any element All elements can be studied All ions come directly from fission Ion rate in the formed beam corresponds to the independent fission yield

6 Isotopic purification with JYFLTRAP

7 Isotopic purification with JYFLTRAP Getting ion bunch from cooler in to the trap Gotcha! Ions are cooled and the cooled ions to a larger radius centers the chosen ones are dipole excited first Mass selective quadrupole excitation > 7 ms, typical 6 ms Finally, out of the trap they go namely, those that go 1.5 SPLAT

8 Isotopic purification with JYFLTRAP 1.5 SPLAT

9 From mass spectra to yield distribution Rh Y 114 Pd 114 Ag A = 114 Y/Y r 1 Fit results for Pd c 2 = <A> = ±.723 W = ± Y = 1 ± Reference spectrum A = Y r 115 Pd 115 Ag Rh 115 Cd Rh 116 Pd 116 Ag A = x 1

10 Mass dependency of the stopped ions Simulations made by Uppsala Universitet collaboration

11 Impact of stable isotope ions Space charge in the trap is an issue for yield measurements. Reduce amount of stable ions: - better purified system Lower ion rate: - ratio may kill yield anyway Pre-selection: - installing MR-TOF

12 Limits of resolving: overlapping isotopes Overlapping peaks can be resolved using gaussian fit Sufficient in this case uncertainty order of 1%

13 Even more challenging resolving by fit

14 Task for a fit master at limits of the first trap MRP (m/dm) = 2 currently the best the purification trap can do Higher MRP required for 132 Sn region and heaviest fragments (close to stability) Use of the second trap (precison trap) improves MRP by a factor of > 5 - Ramsey cleaning EPJA (212) 48:46 - PI ICR (Phase-Imaging Ion-Cyclotron- Resonance) PRL11,8251 (213)

15 Presenting the results Fit results for Zr c 2 = <A> = ± W = ±.5772 Y = ± Rubchenya 6 4 Wahl (JEFF-UKFY4) 2 Fit results for Pd c 2 = <A> = ±.723 W = ± Y = 1 ± W A max

16 25 MeV p + nat U fission : widths 1 Fit results for Pd c 2 = <A> = ±.723 W = ± Y = 1 ± W Z

17 A UCD - <A> JYVÄSKYLÄN YLIOPISTO 25 MeV p + nat U fission : centroids A UCD = Z A(p+U) Z(p+U) Z

18 From isotopic yields to absolute yields? 14 1 Fit results for Br c 2 = <A> = ±.694 W = ±.1147 Y = 1 ± Fit results for Rb c 2 = <A> = ± W = ± Y = 1 ± Fit results for In c 2 =.3896 <A> = ±.7768 W = ± Y = 1 ± Fit results for Y c 2 = <A> = ± W = ± Y = 1 ± Fit results for Pd c 2 = <A> = ±.723 W = ± Y = 1 ± Fit results for Ru c 2 = <A> = ±.5538 W = ±.5741 Y = 1 ±

19 Independent absolute yields? 14 1 Fit results for Br c 2 = <A> = ±.694 W = ±.1147 Y = 1 ± Fit results for Rb c 2 = <A> = ± W = ± Y = 1 ± Fit results for In c 2 =.3896 <A> = ±.7768 W = ± Y = 1 ± Fit results for Y c 2 = <A> = ± W = ± Y = 1 ± Fit results for Pd c 2 = <A> = ±.723 W = ± Y = 1 ± Fit results for Ru c 2 = <A> = ±.5538 W = ±.5741 Y = 1 ± Fission mass cross section Baba et al, / mb MeV p U Baba et al measured and reflected points Fit to Baba Isaev et al 26.5 MeV p U, fragments Complementary elements yields required equal Mass number A 14 16

20 Future: neutron induced fission - concept Target chamber SPIG Cooling water He buffer gas 1 mm Be target Fission target

21 Neutron converter design Al block Proton beam 3 MeV, 1 μa M. Lantz, D. Gorelov et al., Phys. Scr. T15 (212) Be target Cooling water

22 Neutron converter flux test (March 214) NAA target positions 23 cm TFBC with 238 U target

23 IGISOL group and relevant collaboration: JYFL-IGISOL: H. Penttilä, A. Jokinen, I.D.Moore, J. Äystö, V.A. Rubchenya, S. Rinta-Antila, V. Kolhinen, T. Eronen, A. Kankainen, A. Voss, D. Gorelov, J. Hakala, V. Simutkin, V. Sonnenschein, I. Pohjalainen, J. Koponen, J. Reinikainen Uppsala University: A. Al-Adili, K. Jansson, M. Lantz, A. Solders, C. Gustavsson, A.Mattera, A. V. Prokofiev, V. Rakopoulos, D.Tarrío, S. Wiberg, M.Österlund, S. Pomp This work has been supported by Academy of Finland via several projects and the Centre of Excellence program, and by EU via ERINDA project (21-213) and will be supported by CHANDA project ( )