| 11. |
- Sohler, D., et al.
(författare)
-
Yrast states of the proton drip line nucleus 106 Sb
- 1999
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993 .- 0556-2813 .- 1089-490X. ; 59:3, s. 1324-1327
-
Tidskriftsartikel (refereegranskat)abstract
- Yrast states of [Formula Presented] have been investigated in the [Formula Presented] reaction using in-beam [Formula Presented]-spectroscopic methods and in the [Formula Presented] reaction performing delayed [Formula Presented] and conversion electron studies. A new isomeric state was found at 103 keV with [Formula Presented] The number of states and transitions in the proposed level scheme have been doubled. The experimental results are discussed within the framework of the shell model. © 1999 The American Physical Society.
|
|
| 12. |
- Abdo, A. A., et al.
(författare)
-
FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR
- 2009
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 696:2, s. 1084-1093
-
Tidskriftsartikel (refereegranskat)abstract
- The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new gamma-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high-quality pulse profile, with some 32,400 pulsed photons at E >= 0.03 GeV, shows new features, including pulse structure as fine as 0.3 ms and a distinct third peak, which shifts in phase with energy. We examine the high-energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power-law index of Gamma = 1.51(-0.04)(+0.05) with an exponential cutoff at E-c = 2.9 +/- 0.1 GeV. Spectral fits with generalized cutoffs of the form e(-(E/Ec)b) require b <= 1, which is inconsistent with magnetic pair attenuation, and thus favor outer-magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding pulsar wind nebula.
|
|
| 13. |
- Axelsson, Magnus, et al.
(författare)
-
Measuring energy dependent polarization in soft γ-rays using Compton scattering in PoGOLite
- 2007
-
Ingår i: Astroparticle Physics. - : Elsevier BV. - 0927-6505. ; 28:3, s. 327-337
-
Tidskriftsartikel (refereegranskat)abstract
- Linear polarization in X- and γ-rays is an important diagnostic of many astrophysical sources, foremost giving information about their geometry, magnetic fields, and radiation mechanisms. However, very few X-ray polarization measurements have been made, and then only mono-energetic detections, whilst several objects are assumed to have energy dependent polarization signatures. In this paper, we investigate whether detection of energy dependent polarization from cosmic sources is possible using the Compton technique, in particular with the proposed PoGOLite balloon-experiment, in the 25–100 keV range. We use Geant4 simulations of a PoGOLite model and input photon spectra based on Cygnus X-1 and accreting magnetic pulsars (100 mCrab). Effective observing times of 6 and 35 h were simulated, corresponding to a standard and a long duration flight, respectively. Both smooth and sharp energy variations of the polarization are investigated and compared to constant polarization signals using chi-square statistics. We can reject constant polarization, with energy, for the Cygnus X-1 spectrum (in the hard state), if the reflected component is assumed to be completely polarized, whereas the distinction cannot be made for weaker polarization. For the accreting pulsar, constant polarization can be rejected in the case of polarization in a narrow energy band with at least 50% polarization, and similarly for a negative step distribution from 30% to 0% polarization.
|
|
| 14. |
- Bergenius, S., et al.
(författare)
-
Proton irradiation response of CsI(Tl) crystals for the GLAST calorimeter
- 2003
-
Ingår i: 2003 IEEE Nuclear Science Symposium Conference Record. - : IEEE Press. - 0780382579 ; , s. 1096-1099
-
Konferensbidrag (refereegranskat)abstract
- The electromagnetic calorimeter of the Gamma-Ray Large Area Space Telescope (GLAST) consists of 16 towers of CsI(Tl) crystals. Each tower contains 8 layers of crystals (each 326.0x26.7x19.9 mm3) arranged in a hodoscopic fashion. The crystals are read out at both ends with photodiodes. Crystals produced by Amcrys-H (Ukraine) are used. A full size crystal was irradiated with a 180 MeV proton beam and the radiation induced attenuation was measured. The induced radioactivity of the crystal was also studied. In this paper we will discuss the damage due to proton irradiation and compare this with the expected in-orbit background flux.
|
|
| 15. |
- Bergenius, S., et al.
(författare)
-
Radiation hardness tests of CSI(Tl) crystals for the GLAST electromagnetic calorimeter
- 2003
-
Ingår i: Proceedings of 28th International Cosmic Ray Conference. ; , s. 2787-2790
-
Konferensbidrag (refereegranskat)abstract
- The electromagnetic calorimeter of the Gamma ray Large Area Space Telescope(GLAST) consists of 16 towers of CsI(Tl) crystals. Each tower contains 8layers of crystals (each 326.0×26.7×19.9 mm3) arranged in a hodoscopic fashion.The crystals are read out at both ends with PIN photodiodes. Crystals producedby Amcrys-H (Ukraine) are used. As a part of the quality control procedureduring crystal production, samples from the uncut boules are systematically irradiatedwith gamma rays from a 60Co source. Studies have also been carried outto verify the correspondence between the post-irradiation properties of the boulesamples and the full size crystals which are subsequently cut from the boule. Thefull size crystals have also been irradiated with a 180 MeV proton beam and theradiation induced attenuation measured.
|
|
| 16. |
- Cederkall, J, et al.
(författare)
-
First evidence for excited states in In-101
- 1996
-
Ingår i: PHYSICAL REVIEW C-NUCLEAR PHYSICS. - : AMER INST PHYSICS. - 0556-2813. ; 53:4, s. 1955-1958
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The first evidence for excited states in In-101 is presented. In-101 is the lightest In isotope observed in an in-beam experiment. Two gamma-ray transitions at 1309 and 341 keV, respectively, are strong candidates for a cascade to the ground state in this
|
|
| 17. |
- Cederkall, J, et al.
(författare)
-
Maximum spin aligned states in Ag-98(47)51
- 1998
-
Ingår i: EUROPEAN PHYSICAL JOURNAL A. - : SPRINGER VERLAG. - 1434-6001. ; 1:1, s. 7-9
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- New excited states have been observed in the neutron deficient isotope Ag-98 following the Ni-58+Cr-50-->Te-108* heavy-ion reaction. One of these states may be interpreted as a maximum spin aligned state of the pi g(9/2)(-3) nu vg(7/2) configuration. Othe
|
|
| 18. |
- Danko, I, et al.
(författare)
-
Collective and broken pair states of Ga-65,Ga-67
- 1999
-
Ingår i: PHYSICAL REVIEW C-NUCLEAR PHYSICS. - : AMERICAN PHYSICAL SOC. - 0556-2813. ; 59:4, s. 1956-1974
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Excited states of Ga-65 and Ga-67 nuclei were populated through the C-12(Ni-58,alpha p) and C-12(Ni-58,3p) reactions, respectively, and investigated by in-beam gamma-ray spectroscopic methods. The NORDBALL array equipped with a charged particle ball and 1
|
|
| 19. |
- Ideguchi, Eiji, et al.
(författare)
-
Superdeformation in 91Tc
- 2000
-
Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 492:3-4, s. 245-253
-
Tidskriftsartikel (refereegranskat)abstract
- A high-spin rotational band with 11 gamma -ray transitions has barn observed in Tc-91. The dynamical moment of inertia as well as the transition quadrupole moment of 8.1(-1.4)(+1.9) eb measured for this band show the characteristics of a superdeformed band. However, the shape is more elongated than in the neighbouring A = 80-90 superdeformed nuclei. Theoretical interpretations of the band within the cranked Strutinsky approach based on two different Woods-Saxon potential parameterisations are presented. Even though an unambiguous configuration assignment proved difficult, both calculations indicate a larger deformation and at least three additional high-N intruder orbitals occupied compared to the lighter SD nuclei. (C) 2000 Elsevier Science B.V. All rights reserved.
|
|
| 20. |
- JERRESTAM, D, et al.
(författare)
-
COLLECTIVE EXCITATIONS IN CD-106
- 1994
-
Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 571:2, s. 393-412
-
Tidskriftsartikel (refereegranskat)abstract
- High Spin states in 106Cd were populated by the reactions Zr-94(O-17, 5n) and Ge(S-32, 4n) at 80 MeV and at 148 MeV, respectively. The gamma-decay was studied by gamma-spectroscopic methods using the Nordball multi-detector army. Protons and alpha-particles were detected in particle detector system, thus selecting the neutron channel. The experiment included gamma-ray yields, gammagamma-coincidences and gamma-ray angular relation measurements. Collective bands extending up to spin 26+, 20- and 21-, have been observed in 106Cd. A new lifetime Of 11(-3)+6 ns for the 16+ state at 7118.7 keV has been found. Both total Routhian surfaces and spin diabatic surfaces have been calculated and used for assigning quasiparticle configurations to the bands. The (+, 0) band is assigned as a nuh11/2(2) configuration below I = 16+ and at higher spins suggested to be built on a pig9/2(2)nuh11/2(2) configuration. The large hindrance observed for the decay from the 16+ state supports the latter assignment. With the alignment of the nuh11/12(2) pair the deformation is predicted to change from (epsilon2,gamma) = (0.13,-2-degrees) to (0.17, 4-degrees). The configuration of the negative parity bands is assigned as either a nuh11/2(1)d5/2(1) or a nuh11/2(1)(g7/2xd5/2)1, With (epsilon2, gamma) = (0.14,9-degrees.
|
|
