Search results for "Internal conversion"

Experimental investigation of the 02+ band in Sm154 as a β-vibrational band

2014

Abstract A study of Sm 154 through γ -ray and internal conversion electron coincidence measurements was performed using the Silicon And GErmanium spectrometer (SAGE). An upper limit for the ρ 2 ( E 0 ; 2 2 + → 2 1 + ) and measurement of the ρ 2 ( E 0 ; 4 2 + → 4 1 + ) monopole transitions strengths were determined. The extracted transition strength for each is significantly lower than that predicted by either the Bohr and Mottelson β -vibration description or the interacting boson model. Hence, the long standing interpretation of these states as a collective band built on the 0 2 + state, which is conventionally assigned as a Bohr and Mottelson β vibration is questionable.

In-beam study of 253No using the SAGE spectrometer

2017

The heavy actinide nucleus 253No (Z = 102) was studied using the (S)ilicon (A)nd (Ge)rmanium (SAGE) spectrometer allowing simultaneous in-beam $\gamma$ -ray and conversion electron spectroscopy at the accelerator laboratory of the University of Jyvaskyla. Using the recoil-tagging technique, $\gamma$ -electron coincidences have allowed for the extension of the level scheme in the lower-spin region of the yrast band. In addition, internal conversion coefficient (ICC) measurements to establish the multipolarity of transitions have been performed. Measurement of the interband-intraband branching ratios supports the assignment of the Nilsson band-head configuration $9/2^{-}[734]$ assigned in pre…

In-beam electron spectrometer used in conjunction with a gas-filled recoil separator

2004

The conversion-electron spectrometer SACRED has been redesigned for use in conjunction with the RITU gas-filled recoil separator. The system allows in-beam recoil-decay-tagging (RDT) measurements of internal conversion electrons. The performance of the system using standard sources and in-beam is described.

Spectroscopy of34,35Sibyβdecay:sd−fpshell gap and single-particle states

2001

The new neutron-rich nuclei231Fr and231Ra

1985

The new neutron-rich isotope231Fr has been produced in a spallation reaction of238U induced by 600 MeV protons and identified by mass-separation and decay spectroscopy. In addition, the so far unknown231Ra and the known231Ac have been observed as daughter products. The Z-assignments were performed via the decay of KX-rays, and genetic relationships. Half-lives of 17.5(8) s and 103(3) s were obtained for231Fr and231Ra, respectively.

Evaluation of high-energy brachytherapy source electronic disequilibrium and dose from emitted electrons

2009

Purpose: The region of electronic disequilibrium near photon-emitting brachytherapysources of high-energy radionuclides ( C 60 o , C 137 s , I 192 r , and Y 169 b ) and contributions to total dose from emitted electrons were studied using the GEANT4 and PENELOPEMonte Carlo codes. Methods: Hypothetical sources with active and capsule materials mimicking those of actual sources but with spherical shape were examined. Dose contributions due to sourcephotons, x rays, and bremsstrahlung; source β − , Auger electrons, and internal conversionelectrons; and water collisional kerma were scored. To determine if conclusions obtained for electronic equilibrium conditions and electrondose contribution t…

A charge plunger device to measure the lifetimes of excited nuclear states where transitions are dominated by internal conversion

2020

Abstract A charge plunger device has been commissioned based on the DPUNS plunger (Taylor et al., 2013) using the in-flight mass separator MARA at the University of Jyvaskyla. The 152 Sm (32 S ,4 n )180 Pt reaction was used to populate excited states in 180 Pt . A lifetime measurement of the 2 1 + state was performed by applying the charge plunger technique, which relies on the detection of the charge state-distribution of recoils rather than the detection of the emitted γ rays. This state was a good candidate to test the charge plunger technique as it has a known lifetime and depopulates through a converted transition that competes strongly with γ -ray emission. The lifetime of the 2 1 + s…

Direct detection of the elusive 229thorium isomer: Milestone towards a nuclear clock

2017

Recently, the first direct detection of the long-searched low-lying isomeric first excited state of 229Th could be realized via its internal conversion decay branch, which confirms the isomer's existence and lays the foundation for precise studies of its decay parameters, in particular its half-life and excitation energy. Follow-up studies confirmed the theoretically expected lifetime reduction by about 109 of neutral 229mTh compared to charged isomers with τ∼10 μS thus emphasizing the need to efficiently suppress internal conversion when aiming for the detection of a potential photonic decay branch of 229mTh. Work towards precisely determining the excitation energy of the thorium isomer is…

Photostability and Photoreactivity in Biomolecules: Quantum Chemistry of Nucleic Acid Base Monomers and Dimers

2008

The great potentials of high-level ab initio methods, in particular, the CASPT2//CASSCF protocol, are fully illustrated through: (i) the study of ultrafast energy relaxation in DNA/RNA base monomers, (ii) the intrinsic population mechanism of the lowest triplet state, and (iii) how bioexcimers can be considered as precursors of charge transfer and photoinduced reactivity. In order to describe these processes properly, the presence of conical intersections (CIs) and the topology of the involved pathways have to be determined correctly. Thus, in theoretical calculations the dynamic electronic correlation has to be considered. The accessibility of the CIs (or the seam of CIs) becomes crucial t…

The SPEDE spectrometer

2017

8 pags., 10 figs., 2 tabs.