| 1. |
- Bruzzi, M, et al.
(författare)
-
Radiation-hard semiconductor detectors for SuperLHC
- 2005
-
Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 541:1-2, s. 189-201
-
Tidskriftsartikel (refereegranskat)abstract
- An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035 cm-2 s-1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 1016cm-2. The CERN-RD50 project "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.
|
|
| 2. |
- Ertoprak, Aysegul, et al.
(författare)
-
Evidence for octupole collectivity in 172Pt
- 2020
-
Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 56:2
-
Tidskriftsartikel (refereegranskat)abstract
- Excited states in the extremely neutron-deficient nucleus 172Pt were populated via 96Ru(78Kr,2p) and 92Mo(83Kr,3n) reactions. The level scheme has been extended up to an excitation energy of ~ 5 MeV and tentative spin-parity assignments up to Iπ = 18+. Linear polarization and angular distribution measurements were used to determine the electromagnetic E1 character of the dipole transitions connecting the positive-parity ground-state band with an excited side-band, firmly establishing it as a negative-parity band. The lowest member of this negative-parity structure was firmly assigned spin-parity 3-. In addition, we observed an E3 transition from this 3- state to the ground state, providing direct evidence for octupole collectivity in 172Pt. Large-scale shell model (LSSM) and total Routhian surface (TRS) calculations have been performed, supporting the interpretation of the 3- state as a collective octupole-vibrational state.
|
|
| 3. |
- Petrache, C. M., et al.
(författare)
-
Evidence of chiral bands in even-even nuclei
- 2018
-
Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 97:4
-
Tidskriftsartikel (refereegranskat)abstract
- Evidence for chiral doublet bands has been observed for the first time in the even-even nucleus Nd136. One chiral band was firmly established. Four other candidates for chiral bands were also identified, which can contribute to the realization of the multiple pairs of chiral doublet bands (MχD) phenomenon. The observed bands are investigated by the constrained and tilted axis cranking covariant density functional theory (TAC-CDFT). Possible configurations have been explored. The experimental energy spectra, angular momenta, and B(M1)/B(E2) values for the assigned configurations are globally reproduced by TAC-CDFT. Calculated results support the chiral interpretation of the observed bands, which correspond to shapes with maximum triaxiality induced by different multiquasiparticle configurations in Nd136.
|
|
| 4. |
- Taylor, M. J., et al.
(författare)
-
Oblately deformed isomeric proton-emitting state in Lu-151
- 2015
-
Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 91:4
-
Tidskriftsartikel (refereegranskat)abstract
- Gamma rays from excited states feeding a proton-emitting isomeric-state in Lu-151 have been observed for the first time. Comparison with state-of-the-art nonadiabatic quasiparticle calculations indicates an oblately deformed, 3/2(+) proton-emitting state with a quadrupole deformation of beta(2) = -0.11. The calculations suggest an increase in quadrupole deformation, to beta(2) = -0.18, with increasing spin which is understood in terms of the mixing of Nilsson states at the Fermi surface. It is also shown that the proton decay half-life is consistent with that from a 3/2(+) state with a quadrupole deformation of beta(2) = -0.12.
|
|
| 5. |
- Gillespie, S. A., et al.
(författare)
-
Identification of a 6.6 μ s isomeric state in Ir 175
- 2019
-
Ingår i: Physical Review C. - 2469-9985. ; 99:6
-
Tidskriftsartikel (refereegranskat)abstract
- An experiment has been performed to study excited states in the neutron-deficient nucleus Ir175 via the use of the JUROGAM II high-purity germanium detector array and the RITU gas-filled separator at JYFL, Jyväskylä. By using isomer tagging, an isomeric state with a half-life of 6.58(15) μs has been observed in Ir175 for the first time. It has been established that the isomer decays via a 45.2 (E1)-26.1 (M1) keV cascade to new states below the previously reported ground state in Ir175 with Iπ=(5/2-). We now reassign this (5/2-) state to the isomeric state discovered in this study.
|
|
| 6. |
- Gillespie, S. A., et al.
(författare)
-
Identification of sub- μ s isomeric states in the odd-odd nucleus Au 178
- 2021
-
Ingår i: Physical Review C. - 2469-9985. ; 103:4
-
Tidskriftsartikel (refereegranskat)abstract
- The neutron-deficient gold (Z=79) isotopes in the vicinity of the neutron midshell N=104 provide prolific examples of shape coexistence and isomerism at low excitation energy. They can be probed via a number of different experimental techniques. In this study, two new isomeric states with half-lives of 294(7) and 373(9) ns have been observed in the neutron-deficient odd-odd nuclide Au178 (N=99) in an experiment at the RITU gas-filled separator at JYFL, Jyväskylä. This result was achieved due to the use of a segmented planar germanium detector with a high efficiency at low energies. By applying the recoil-decay tagging technique, they were assigned to decay to two different long-lived α-decaying states in Au178.
|
|
| 7. |
- Grahn, T., et al.
(författare)
-
Excited states and reduced transition probabilities in Os-168
- 2016
-
Ingår i: PHYSICAL REVIEW C. - : American Physical Society. - 2469-9985. ; 94:4
-
Tidskriftsartikel (refereegranskat)abstract
- The level scheme of the neutron-deficient nuclide Os-168 has been extended and mean lifetimes of excited states have been measured by the recoil distance Doppler-shift method using the JUROGAM gamma-ray spectrometer in conjunction with the IKP Koln plunger device. The 168Os. rays were measured in delayed coincidence with recoiling fusion-evaporation residues detected at the focal plane of the RITU gas-filled separator. The ratio of reduced transition probabilities B(E2; 4(1)(+)-> 2(1)(+))/B(E2; 2(1)(+)-> 0(1)(+)) is measured to be 0.34(18), which is very unusual for collective band structures and cannot be reproduced by interacting boson model (IBM-2) calculations based on the SkM* energy-density functional.
|
|
| 8. |
- Hodge, D., et al.
(författare)
-
Identification of a dipole band above the Iπ=31/2- isomeric state in Pb 189
- 2015
-
Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 92:5
-
Tidskriftsartikel (refereegranskat)abstract
- A dipole band of six transitions built upon a firmly established Iπ=31/2- isomeric state has been identified in Pb189 using recoil-isomer tagging. This is the lightest odd-mass Pb nucleus in which a dipole band is known. The dipole nature of the new transitions has been confirmed through angular-intensity arguments. The evolution of the excitation energy and the aligned-angular momentum of the states in the new dipole band are compared with those of dipole bands in heavier, odd-mass lead isotopes. This comparison suggests that the new band in Pb189 is based upon a π[s1/2-2h9/2i13/2]11- - ν[i13/2+-1]13/2+ configuration. However, the increased aligned-angular momentum in Pb189 may suggest evidence for a reduced repulsive proton/neutron-hole interaction compared to dipole bands in the heavier mass isotopes.
|
|
| 9. |
- Petrache, C. M., et al.
(författare)
-
Collective rotation of an oblate nucleus at very high spin
- 2019
-
Ingår i: Physical Review C. - : American Physical Society (APS). - 2469-9985 .- 2469-9993. ; 99:4
-
Tidskriftsartikel (refereegranskat)abstract
- A sequence of nine almost equidistant quadrupole transitions is observed in Nd137. The sequence represents an extremely regular rotational band that extends to a spin of about 75/2 and an excitation energy of ≈4.5MeV above yrast. Cranked mean-field calculations of the Nilsson-Strutinsky type suggest an oblate shape for the band. They reproduce the observed I(I+1) dependence of the rotational energy whereas predicting a pronounced decrease in the deformation, which is the hallmark of antimagnetic rotation.
|
|
| 10. |
- Saygi, B., et al.
(författare)
-
Reduced transition probabilities along the yrast line in W-166
- 2017
-
Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 96:2
-
Tidskriftsartikel (refereegranskat)abstract
- Lifetimes of excited states in the yrast band of the neutron-deficient nuclide W-166 have been measured utilizing the DPUNS plunger device at the target position of the JUROGAM II gamma-ray spectrometer in conjunction with the RITU gas-filled separator and the GREAT focal-plane spectrometer. Excited states in W-166 were populated in the Mo-92(Kr-78, 4p) reaction at a bombarding energy of 380 MeV. The measurements reveal a low value for the ratio of reduced transitions probabilities for the lowest-lying transitions B(E2; 4(+)-> 2(+)) / B(E2; 2(+)-> 0(+)) = 0.33(5), compared with the expected ratio for an axially deformed rotor (B-4/2 = 1.43).
|
|
