Dimitar Tonev, Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences Lifetime measurements in mass regions A=100 and A=130 as a test for chirality in nuclear systems

“I call any geometrical figure, or group of points, chiral, and say it has chirality, if its image in a plane mirror, ideally realized, cannot be brought to coincide with itself.” - Lord Kelvin 1904 Chemistry: molecules with opposite handedness react differently in similar environments Biology: DNA has right and left-handed “screws” Particle Physics

The energies of the excited states for the left-handed and right-handed systems should be identical V. I. Dimitrov et al, PRL 84 (2000) 5732 Nuclear Physics: Current distributions in nuclei

A~130 Odd-Odd (  h 11/2 h 11/2 )‏ 132 Cs, 130 Cs, 128 Cs, 126 Cs, 124 Cs 134 La, 132 La, 130 La 134 Pr, 132 Pr 136 Pm 140 Eu, 138 Eu Odd-A (  (h 11/2 ) 2 h 11/2 )‏ 135 Nd A~105 Odd-Odd (  g 9/2 h 11/2 )‏ 106 Ag, 106 Rh, 104 Rh, 102 Rh 100 Tc, Odd-A (  g 9/2  h 11/2 ) 2 )‏ 105 Rh, 103 Rh A~190 Odd-Odd (  h 9/2 i 13/2 )‏ 188 Ir, 198 Tl A~80‏ Odd-Odd (  g 9/2 g 9/2 )‏ 78 Br, 80 Br Odd-A (  g 9/2 ) 2  g 9/2 ))‏ 79 Kr

Chiral candidates bands in 134 Pr C. Petrache et al., Nucl. Phys. A 597 (1996) 106. K. Starosta et al., Nucl. Phys. A 682 (2001) 375c.

Comparison of the experimental doublet of nearly degenerate positive-parity bands in 134 Pr with the predictions of the TQPTR D. Tonev et al., Phys. Rev. C 76 (2007)

Comparison of the experimental doublet of nearly degenerate positive-parity bands in 134 Pr with the predictions of the IBFFM S. Brant et al, PRC 69 (2004)

Details:  Euroball experiment at IReS Strasbourg, Vivitron accelerator  Cologne plunger device  Reaction: 119 Sn( 19 F,4n) 134 Pr  19 F beam with an energy of 87MeV  Target: 0.5 mg/cm Sn (enriched to 90%) evaporated on a 1.8 mg/cm Ta backing  Stopper: 6 mg/cm 2 thick 197 Au  20 measured distances from 0.1 to 2500 microns  10 days measurement  v/c ~ 1.0(1) %

Analysis details:  10 rings of detectors.  1 h subruns.  Detectors selection.  Stopping power is fixed from RDDS part.  DSAM effects included in RDDS analysis  Comparison with the previous lifetime measurements.

Evolution of the lineshapes of the transitions  (416 keV) and  (324 keV) with the distance

Details:  Euroball experiment at IReS Strasbourg, Vivitron accelerator  Reaction: 119 Sn( 19 F,4n) 134 Pr  19 F beam with an energy of 83 MeV  Target: 0.7 mg/cm Sn (enriched to 90%) evaporated on a 9.5 mg/cm Ta backing  4 days measurement  v/c ~ 1.0(1) %

Lineshape analysis of the 1027 keV transition in the Band 1 and determination of the lifetime of state according to DDCM.

Comparison of the polarization experimental data for (7 1 + )  (6 1 - ), ( )  ( ) and ( )  ( ) transitions.

D. Tonev et. al., Phys. Rev. Lett. 96 (2006)

 Excited states in 102 Rh and 102 Ru were populated through the fusion- evaporation reactions 94 Zr( 11 B,3n) and 94 Zr( 11 B,2np), respectively.  The target was a thin film of 0.9 mg/cm 2 94 Zr evaporated onto 8 mg/cm Au backing.  The beam of 11 B with an energy of 36 MeV was provided by the 15- UD Pelletron accelerator of the Inter University Accelerator Centre (IUAC), New Delhi. v/c=0.9(2)%.  The cascades of gamma rays were registered by the Indian National Gamma Array (INGA) that accommodated 15 Ge Clover detectors in a 4π geometry.  Gain matching and efficiency calibration of the clover detectors were carried out with 152 Eu and 133 Ba sources.

Indian National Gamma Array (INGA)  Up to twenty four Compton- suppressed Clover germanium detectors with a total photopeak efficiency of about 5%.  5 rings of Clover detectors at θ={148º,123º,90º,57º,32º}.  Each Clover detector can be used as a four-fold Compton polarimeter to measure linear polarization spectra. S. Muralithar et al. NIMA 622 (2010)

Partial level scheme of 102 Rh  The level scheme of 102 Rh was determined by analysing single and double gated coincidence spectra.  The gamma-gamma coincidence matrix was then fitted with the gtkesc program from the Radware package. Band 1 Band 2 spin parity

Linear polarization spectrum

Partial level scheme of 102 Rh  The transitions between the two bands are of magnetic multipolar character.  Assumed to be M1/E2 with a dominant M1 component. ? spin

Symmetries of the angular-correlation function W( θ 1,θ 2,Δ ɸ )  These symmetry constraints allow the pairs of detectors to be classified into unique geometry groups.  For INGA there are 210 pairs of detectors, respectively gamma-gamma coincidence matrices, that can be sorted into 25 unique geometry groups.

Angular correlations analysis of the 4 + → 2 + → 0 + cascade in 102 Ru DCO-pattern determined with the CORLEONE program, I. Wiedenhover et al. PRC 58 (1998) 721.

Angular correlations analysis of the 11 - → 10 - → 9 - cascade in 102 Rh DCO-pattern determined with the CORLEONE program, I. Wiedenhover et al. PRC 58 (1998) 721. spin

Line shape analysis of the 669 KeV transition in Band 1 of 102 Rh Θ=32 0 Θ= KeV τ 32 =427 τ 148 = Rh pg9/2 x nh11/2 Band 1

Comparison of the experimentally determined and theoretically calculated excitation energies of chiral candidates bands in 102Rh

Energies of the levels in the chiral candidate bands of 102Rh as a function of the spin I compared to the results of the TQPTR calculations

Experimentally derived and theoretically calculated B(E2) and B(M1) transition strengths in chiral candidate bands in 102Rh.

Using advanced methods for lifetime analysis 14 lifetimes in the both chiral candidate bands in 134 Pr are determined for the first time. The experimentally observed transition matrix elements are reproduced by IBFFM, taking into account the fluctuation of nuclear shape. The experimental difference between the B(E2) values cannot be reproduced assuming a rigid triaxial shape (TQPTR) which also result in a pronounced staggering of the B(M1) values not found in the experimental data. The chirality in 134 Pr has mainly a dynamic character, where the coupling due to shape fluctuations seems to play a central role.

* A new band has been found in 102 Rh. * Linear polarization measurements have shown that the parity of the band is negative. * Angular correlation analysis clearly confirms a spin hypothesis 13 - → 12 - →11 - →10 - for the new band. * Using advances methods for lifetime analysis 8 lifetimes in both chiral candidate bands are determine for the first time. * Two quasiparticle plus triaxial rotor model calculations show that triaxial parameter gamma is equal to 20 o. In such case the agreement of excitation energies, B(M1) and B(E2) values are in good agreement with the experimentally derives ones.

Milan, 2003

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