Radiative electron capture in the first forbidden unique decay of 81Kr

The photon spectrum accompanying the orbital K-electron capture in the first forbidden unique decay of 81Kr was measured. The total radiation intensity for the photon energies larger than 50 keV was found to be 1.47(6) x 10^{-4} per K-capture. Both the shape of the spectrum and its intensity relative to the ordinary, non-radiative capture rate, are compared to theoretical predictions. The best agreement is found for the recently developed model which employs the length gauge for the electromagnetic field.Comment: 7 pages, 6 figure

Shape Isomerism at N = 40: Discovery of a Proton Intruder in 67Co

The nuclear structure of 67Co has been investigated through 67Fe beta-decay. The 67Fe isotopes were produced at the LISOL facility in proton-induced fission of 238U and selected using resonant laser ionization combined with mass separation. The application of a new correlation technique unambiguously revealed a 496(33) ms isomeric state in 67Co at an unexpected low energy of 492 keV. A 67Co level scheme has been deduced. Proposed spin and parities suggest a spherical (7/2-) 67Co ground state and a deformed first excited (1/2-) state at 492 keV, interpreted as a proton 1p-2h prolate intruder state.Comment: 4 pages, 5 figures, preprint submitted to Physical Review Letter

Searching for ß-delayed protons from 11 Be

ISOLDE Workshop and Usersmeeting. Wednesday 05 December - Friday 07 December 2018 .CERN ( ISOLDE User Support. PH Departmen - CERN/CH-1211 Geneve 23). --.https://indico.cern.ch/event/736872/contributions

4-1BBL-containing leukemic extracellular vesicles promote immunosuppressive effector regulatory T cells

Chronic and acute myeloid leukemia evade immune system surveillance and induce immunosuppression by expanding proleukemic Foxp31 regulatory T cells (Tregs). High levels of immunosuppressive Tregs predict inferior response to chemotherapy, leukemia relapse, and shorter survival. However, mechanisms that promote Tregs in myeloid leukemias remain largely unexplored. Here, we identify leukemic extracellular vesicles (EVs) as drivers of effector proleukemic Tregs. Using mouse model of leukemia-like disease, we found that Rab27adependent secretion of leukemic EVs promoted leukemia engraftment, which was associated with higher abundance of activated, immunosuppressive Tregs. Leukemic EVs attenuated mTOR-S6 and activated STAT5 signaling, as well as evoked significant transcriptomic changes in Tregs. We further identified specific effector signature of Tregs promoted by leukemic EVs. Leukemic EVs-driven Tregs were characterized by elevated expression of effector/tumor Treg markers CD39, CCR8, CD30, TNFR2, CCR4, TIGIT, and IL21R and included 2 distinct effector Treg (eTreg) subsets: CD301CCR8hiTNFR2hi eTreg1 and CD391TIGIThi eTreg2. Finally, we showed that costimulatory ligand 4-1BBL/CD137L, shuttled by leukemic EVs, promoted suppressive activity and effector phenotype of Tregs by regulating expression of receptors such as CD30 and TNFR2. Collectively, our work highlights the role of leukemic extracellular vesicles in stimulation of immunosuppressive Tregs and leukemia growth. We postulate that targeting of Rab27a-dependent secretion of leukemic EVs may be a viable therapeutic approach in myeloid neoplasms

High-sensitivity study of levels in Al-30 following beta decay of Mg-30

gamma-ray and fast-timing spectroscopy were used to study levels in Al-30 populated following the beta(-) decay of Mg-30. Five new transitions and three new levels were located in Al-30. A search was made to identify the third 1(+) state expected at an excitation energy of similar to 2.5 MeV. Two new levels were found, at 3163.9 and 3362.5 keV, that are firm candidates for this state. Using the advanced time-delayed (ATD) beta gamma gamma (t) method we have measured the lifetime of the 243.8-keV state to be T-1/2 = 15(4) ps, which implies that the 243.8-keV transition is mainly of M1 character. Its fast B(M1; 2(+) -> 3(+)) value of 0.10(3) W.u. is in very good agreement with the USD shell-model prediction of 0.090 W.u. The 1801.5-keV level is the only level observed in this study that could be a candidate for the second excited 2(+) state.Peer reviewe

Updated β -decay measurement of neutron-rich Cu 74

The β decay of neutron-rich Cu74 has been studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. By using a high-resolution mass separator a purified Cu74 beam was obtained, thus allowing decay through its isobar chain to stable Ge74 without any decay chain member dominating. A total of 170γ rays were associated with Cu74β decay with 111 placed in the Zn74 level scheme. Updated β feeding intensities and estimated log(ft) values are presented, and new Jπ assignments are proposed using shell model calculations. The progression of simulated total absorption γ-ray spectroscopy (TAGS) based on proposed levels and β-feeding values from previous measurements to this evaluation are presented and demonstrate the need for a TAGS measurements for this and similar decays

The (n, gamma) campaigns at EXILL

At the PF1B cold neutron beam line at the Institut Laue Langevin, the EXILL array consisting of EXOGAM, GASP and ILL-Clover detectors was used to perform (n, gamma) measurements at very high coincidence rates. About ten different reactions were measured in autumn 2012 using a highly collimated cold neutron beam. In spring 2013, the EXOGAM array was combined with 16 LaBr3(Ce) scintillators in the EXILL&FATIMA campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of the set-ups and present first results from both campaigns

ß-delayed neutron emission of r-process nuclei at the N=82 shell closure

Theoretical models of ß-delayed neutron emission are used as crucial inputs in r-process calculations. Benchmarking the predictions of these models is a challenge due to a lack of currently available experimental data. In this work the ß-delayed neutron emission probabilities of 33 nuclides in the important mass regions south and south-west of 132Sn are presented, 16 for the first time. The measurements were performed at RIKEN using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The values presented constrain the predictions of theoretical models in the region, affecting the final abundance distribution of the second r-process peak at .Peer ReviewedArticle signat per 58 autors/es J. Liu, S. Bae, N.T. Brewer, C.G. Bruno, R. Caballero-Folch, P.J. Coleman-Smith, I. Dillmann, C. Domingo-Pardo, A. Fijalkowska, N. Fukuda, S. Go, C.J. Griffin, R. Grzywacz, J. Ha, L. J. Harkness-Brennan, T. Isobe, D. Kahl, L.H. Khiem, G.G. Kiss, A. Korgul, S. Kubono, M. Labiche, I. Lazarus, P. Morrall, M.R. Mumpower, N. Nepal, R.D. Page, M. Piersa , V.F.E. Pucknell , B.C. Rasco, B. Rubio, K.P. Rykaczewski , H. Sakurai , Y. Shimizu , D.W. Stracener, T. Sumikama , H. Suzuki, J.L. Tain , H. Takeda, A. Tarifeño-Saldivia, A. Tolosa-Delgado , M. Wolinska-Cichocka , R. YokoyamaPostprint (author's final draft