Lifetimes of excited states in Th-229, populated in the beta decay of Ac-229, have been measured using the advanced time-delayed beta gamma gamma(t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new gamma lines have been introduced into the beta-decay scheme of Ac-229 based on results of gamma gamma coincidence measurements. Reduced transition probabilities have been determined for more than 70 gamma transitions in Th-229. Average parallel to D-0 parallel to values of 0.029(1), 0.077(3), and 0.024(5) e fm have been deduced for the lowest K-pi=1/2(+/-),3/2(+/-), and 5/2(+/-) parity partner bands, respectively. Excited states in Th-229 and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, 3/2(+) isomeric state is predicted to be about 10 h. Potential energy surfaces on the (beta(2),beta(3)) plane for the lowest single quasiparticle configurations in Th-229 have been calculated using the Strutinsky method.

The performance of hand-held radioisotope identification devices (RIDS) is still hampered by the performance of the NaI(T1) detectors, which are commonly used in such instruments. In this paper, we continue the search for better detector options. One of the largest single elements ever made, a coplanar CdZnTe (CZT) detector (30 x 15 x 12.1 mm(3) volume 5.45 cm(3) designed by University of Michigan) is compared with a commercially available LaBr3 (Ce) detector (circle divide 1" x 1" volume 12.9 cm(3).) Parameters that are relevant to the performance of isotope identification devices, such as resolution and efficiency as function of the gamma-ray energy, temperature shift, linearity and others are measured and compared. According to measurement results, it seems that for this application LaBr3(Ce) detectors are a viable alternative to CZT detectors; even more so if one bears in mind that LaBr3(Ce) became commercially available only recently and detectors with larger volumes are likely to appear in the near future.

E. Ruchowska,1,∗ W. A. Płóciennik,1,† J. Żylicz,2 H. Mach,3 J. Kvasil,4 A. Algora,5 N. Amzal,6 T. Bäck,7 M. G. Borge,8 R. Boutami,8 P. A. Butler,6 J. Cederkäll,9 B. Cederwall,7 B. Fogelberg,3 L. M. Fraile,9,‡ H. O. U. Fynbo,9 E. Hagebø,10 P. Hoff,10 H. Gausemel,10 A. Jungclaus,8 R. Kaczarowski,1 A. Kerek,7 W. Kurcewicz,2 K. Lagergren,7 E. Nacher,5 B. Rubio,5 A. Syntfeld,1 O. Tengblad,8 A. A. Wasilewski,1 and L. Weissman9 1The Andrzej Sołtan Institute for Nuclear Studies, PL 05-400 Świerk, Poland 2Institute of Experimental Physics, University of Warsaw, PL 00-681 Warsaw, Poland 3Department of Radiation Sciences, University of Uppsala, SE-751 21 Uppsala, Sweden 4Department of Nuclear Physics, Charles University, CZ-18000 Prague 8, Czech Republic 5Instituto de Fı́zica Corpuscular, CSIC-University Valencia, E-46100 Burjassot, Spain 6Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 3BX, United Kingdom 7Physics Department, Royal Institute of Technology, SE-106 91 Stockholm, Sweden 8Instituto de Estructura de la Materia, CSIC, E-28006 Madrid, Spain 9ISOLDE, CERN, CH-1211 Geneva 23, Switzerland 10Department of Chemistry, University of Oslo, Post Office Box 1033 Blindern, N-0315 Oslo, Norway (Received 28 December 2005; published 26 April 2006)

After its introduction in 1994, LuAlO/sub 3/:Ce (LuAP:Ce) encountered problems of (1) low light output, (2) self-absorption of scintillation light, (3) non-proportionality of light output versus energy and (4) poor energy resolution. Studying newly available LuAP:Ce-doped and undoped crystals (from Photonic Materials), we have found that self-absorption is chiefly dependent on the host crystal structure and not on Ce doping. We examined the scintillation properties of these crystals and found 6.8/spl plusmn/0.3% energy resolution for 662 keV for 2 mm /spl times/ 2 mm /spl times/ 10 mm pixels. The intrinsic resolution is equal to 2.8/spl plusmn/0.4% at 2360/spl plusmn/120 phe/MeV (9800/spl plusmn/500 ph/MeV) light yield. These crystals have non-proportionality of 93/spl plusmn/4% at 16 keV and intrinsic energy resolution close to that of YAP:Ce. Fast components of the scintillation comprise only about half of the light that is emitted in 100 microseconds.

The beta(-)-decay of Cs-147 to Ba-147 has been studied by means of gamma- and X-ray spectroscopy. A new level scheme of Ba-147 is significantly modified and extended in comparison to the one previously reported. The Advanced Time-Delayed betagammagamma(t) method has been applied to measure half-lives of the 46.2 and 85.4 keV levels in Ba-147 yielding T-1/2 of 510(80) ps and 370(100) ps, respectively. The lifetime results combined with the deduced internal conversion coefficients allowed to assign M1 multipolarity to three gamma transitions. The B(M1) values obtained for the 39.2, 46.2 and 85.4 keV transitions range from 0.017 to 0.043 W.u. and represent typical B(M1) strength in the Ba-Er region. Model calculations using a shell correction approach with the axiall ' v deformed foods-Saxon potential predict for Ba an octupole deformed ground state with beta(3) = 0.11.

This work presents the results from experiments performed on Lu2SiO5:Ce (LSO:Ce). It looks for potential correlations of light yield non-proportionality and other scintillation properties including intrinsic energy resolution with thermoluminescence properties. Samples were chosen from various crystal batches that were known to have significantly different properties. Single crystal LSO:Ce samples were coupled to an XP2020Q photomultiplier and to large area avalanche photodiodes and measured as a function of gamma-ray energy between 14.7 and 1770 keV at room temperature and also near liquid nitrogen temperature. In order to explain the experimental results obtained from spectrometric methods, the properties of the samples were further studied using thermoluminescence techniques within the temperature range from 250 to 600 K. The relationships between data obtained from these two types of experiments are reported.

. The β - -decay of 147 Cs to 147 Ba has been studied by means of γ- and X-ray spectroscopy. A new level scheme of 147 Ba is significantly modified and extended in comparison to the one previously reported. The Advanced Time-Delayed βγγ(t) method has been applied to measure half-lives of the 46.2 and 85.4 keV levels in 147 Ba yielding T 1/2 of 510(80) ps and 370(100) ps, respectively. The lifetime results combined with the deduced internal conversion coefficients allowed to assign M 1 multipolarity to three γ transitions. The B ( M 1) values obtained for the 39.2, 46.2 and 85.4 keV transitions range from 0.017 to 0.043 W.u. and represent typical B ( M 1) strength in the Ba-Er region. Model calculations using a shell correction approach with the axially deformed Woods-Saxon potential predict for 147 Ba an octupole deformed ground state with β 3 = 0.11.

The performance of a new Photonis XP1472 nine-channel photomultiplier (PMT) was studied with the main emphasis to the photoelectron numbers and photoelectron collection efficiency, as measured with a 10 mm in diameter NaI(Tl) crystal coupled to the separate channels. Simultaneously, energy resolution and crosstalk were measured for all channels with a Cs-137 source. Time jitter and time resolution for an LSO crystal coupled to the different channels were measured for 511 keV annihilation quanta and compared to those measured earlier with XP2020Q PMTs. The studies confirmed high photoelectron collection efficiency in the PMT due to a new design of the input focalisation system.

Europium activated 6LiI crystal (enriched to 96% 6Li) has been studied in neutron and gamma-ray spectrometry. Two crystals of Oslash50 mm times 5 mm and Oslash30 mm times 3 mm size coupled to a calibrated Photonis XP5200 photomultiplier were tested. A response of 6LiI(Eu) to neutrons emitted from a paraffin moderated Pu-Be source has been investigated and the thermal neutron peak has been found to be located at gamma equivalent energy (GEE) of about 3.5 MeV. High sensitivity of the 6LiI(Eu) crystal is demonstrated as the neutron peak is observed at the rate as low as 10-2 counts per second. Apart from neutron spectra a light output, energy resolution and non-proportionality of the 6LiI(Eu) response versus gamma-ray energy have been measured for the two crystals. The light yield of 1.5times104 ph/MeV (about 40% of NaI(Tl)) was obtained and the energy resolution at 662 keV (Cs-137) of 7.5plusmn0.1% was found for the large crystal. The non-proportionality has been measured to have more proportional character as compared to NaI(Tl). Due to the high sensitivity to thermal neutrons and good proportionality against gamma-ray energy, the 6LiI(Eu) crystal was brought under testing with few samples of fissile nuclear materials. Shielded fissile samples can be recognized via detection of neutrons followed spontaneous fission.

. The β^- -decay of 149 Ba to 149 La has been investigated by means of γ - and X-ray spectroscopy, and a partial level scheme of 149 La has been constructed for the first time. It includes thirteen γ -rays and ten excited states. The exotic 149 La is the heaviest lanthanum for which spectroscopic information is now available. We have applied the shell correction approach with the axially deformed Woods-Saxon potential in order to calculate the deformation energy for the 149 La ground state. The deformed ground state was found at β_2 ≃ 0.23, β_3 ≃ 0 and β_4 ≃ 0.12.

Europium activated LiI crystal (enriched to 96% Li) has been studied in neutron and γ-ray spectrometry. Two crystals of ∅50 mm × 5 mm and ∅30 mm × 3 mm size coupled to a calibrated Photonis XP5200 photomultiplier were tested. A response of LiI(Eu) to neutrons emitted from a paraffin moderated Pu-Be source has been investigated and the thermal neutron peak has been found to be located at Gamma Equivalent Energy (GEE) of about 3.5 MeV. High sensitivity of the LiI(Eu) crystal is demonstrated as the neutron peak is observed at the rate as low as 10 counts per second. Apart from neutron spectra a light output, energy resolution and nonproportionality of the LiI(Eu) response versus γ-ray energy have been measured for the two crystals. The light yield of 1.5×10 ph/MeV (about 40% of NaI(Tl)) was obtained and the energy resolution at 662 keV (Cs-137) of 7.5±0.1% was found for the large crystal. The non-proportionality has been measured to have more proportional character as compared to NaI(Tl). Due to the high sensitivity to thermal neutrons and good proportionality against γ-ray energy, the LiI(Eu) crystal was brought under testing with few samples of fissile nuclear materials. Shielded fissile samples can be recognized via detection of neutrons followed spontaneous fission.

The in-situ identification of the isotope causing a radiation alarm at a border monitor is essential for a quick resolution of the case. Commonly, hand-held radioisotope identification devices (RIDs) are used to solve this task. Although a number of such devices are commercially available, we see still a gap between the requirements of the users and what is actually available. Two components are essential for the optimal performance of such devices: i) the quality of the raw data - the gamma spectra, and ii) isotope identification software matching the specifics of a certain gamma detector. In this paper, we investigate new spectral gamma detectors for potential use in hand-held radioisotope identification devices. The standard NaI detector is compared with new scintillation and room temperature semiconductor detectors. The following spectral gamma detectors were included into the study: NaI(Tl), LaCl3(Ce), 6LiI(Eu), CdWO4 , hemispheric and coplanar CZT detectors. In the paper basic spectrometric properties are measured and compared

The $\beta^-$ -decay of 149Ba to 149La has been investigated by means of $\gamma$ - and X-ray spectroscopy, and a partial level scheme of 149La has been constructed for the first time. It includes thirteen $\gamma$ -rays and ten excited states. The exotic 149La is the heaviest lanthanum for which spectroscopic information is now available. We have applied the shell correction approach with the axially deformed Woods-Saxon potential in order to calculate the deformation energy for the 149La ground state. The deformed ground state was found at $\beta_2 \simeq$ 0.23, $\beta_3 \simeq$ 0 and $\beta_4 \simeq$ 0.12.

The beta(-)-decay of Ba-149 to La-149 has been investigated by means of gamma- and X-ray spectroscopy, and a partial level scheme of La-149 has been constructed for the first time. It includes thirteen gamma-rays and ten excited states. The exotic La-149 is the heaviest lanthanum for which spectroscopic information is now available. We have applied the shell correction approach with the axially deformed Woods-Saxon potential in order to calculate the deformation energy for the La-149 ground state. The deformed ground state was found at beta(2) similar or equal to 0.23, beta(3) similar or equal to 0 and beta(4) similar or equal to 0.12.

The properties of CdWO/sub 4/ (CWO) crystals in gamma spectrometry were studied. Several small samples of 10/spl times/10/spl times/3 mm size, typically used in CT X-ray detectors, were tested and then compared to the performance of a larger crystal of 20 mm in diameter and 20 mm in height. The light output, energy resolution, and nonproportionality of the CWO response versus gamma-ray energy, were measured and compared with those of a small BGO to discuss further the origin of the intrinsic resolution of pure undoped scintillating crystals. A high light output of 6500/spl plusmn/200 phe/MeV and a good energy resolution of 6.6/spl plusmn/0.2% for 662 keV gamma rays from a /sup 137/Cs source were measured for the small samples coupled to an XP3212 photomultiplier. Common nonproportionality curves and consequently common intrinsic resolutions of small CWO and BGO suggest that they represent fundamental characteristics of the heavy oxide scintillating material themselves.

The intrinsic energy resolution and nonproportionality of the light yield as a function of gamma ray energies were studied for small BGO crystals at room and liquid nitrogen (LN/sub 2/) temperatures. The study showed that intrinsic resolution of BGO and the light yield non-proportionality as a function of energy do not depend on the crystal temperature. High light outputs of 14000/spl plusmn/ 300 electron-hole pairs and energy resolution of 6.5/spl plusmn/ 0.2% for 662 keV gamma rays were measured with the 9 mm diameter, 4 mm thick crystals, coupled to a Large Area Avalanche Photodiodes and cooled down to LN/sub 2/ temperature. Special attention was paid to analyze the energy resolution of the escape peaks, which were well separated from the full-energy photopeaks due to the good energy resolution of BGO at LN/sub 2/ temperatures and the energy of bismuth K X-rays. The intrinsic energy resolution of the BGO crystal for escape peaks does not show deviations from analysis of total energy absorption photopeaks. This is in spite of the fact that the contributions of X-rays and Auger electron cascade in creation of escape peaks are much smaller than in full-energy peaks. In the small volume crystal, mainly electrons produced in the photoelectric absorption create the escape peaks.