[en] Full text: Advances in laser technology such as chirped pulse amplification have led to the construction of multiterawatt and recently petawatt laser systems and proposed techniques such as optical parametric chirped pulse amplification (OPCPA) promise to continue to extend these boundaries for the foreseeable future. Exciting new fields of research have developed in laser matter interactions as a result of this technology. At laser intensities above 10¹⁸Wcm^-2, relativistic plasmas are created as electrons quiver in the laser field with energies equivalent to their rest mass. Beams of electrons and protons are accelerated and sources of neutrons, high energy γ rays and heavy ions are created. Some of the first results produced by the newly commissioned VULCAN petawatt laser will be presented. These include: a) The production of large quantities of PET isotopes ¹¹C and ¹⁸F which from one laser pulse can produce quantities of these isotopes close to that produced by cyclotrons. Also working with oncology experts in Manchester usable quantities of clinical radio pharmaceutical samples have been extracted. b) Laser induced heavy ion fusion reactions will be described showing how heavy ion intensities are increased by two orders of magnitude when the parasitic protons which are present in all current high intensity laser experiments around the world are eliminated by heating. c) The very exciting laser transmutation of the million year half life ¹²⁹I to 28 min ¹²⁸I will be described. The implications of this will be discussed. d) To finish I shall describe how to use this technology for applications in materials physics

[en] The half-lives in the N=82 region are challenging to measure due to the significant β-delayed neutron decay branches and the population of isomeric states with half-lives comparable to the ground-states. However, by measuring the time distribution of γ-rays rather than that of the β particles, these complications can be eliminated. This requires, however, a very efficient γ-ray spectrometer. The new GRIFFIN array at TRIUMF-ISAC provides the high efficiency required for these measurements. We have measured the half-lives of ^128-130Cd to be 246.2(21) ms for ¹²⁸Cd, 157(8) ms and 147(3) ms for the 3/2+ and 11/2- states of ¹²⁹Cd and 126(4) ms for ¹³⁰Cd. These results improve the precision of the ^128,129Cd half-lives and confirm the shorter half-life of ¹³⁰Cd reported in the literature. However, the reduced quenching of the GT operator implied by the result leads to a reduction in the calculated half-lives of the other N=82 waiting point nuclei and results in a large discrepancy with the reported half-life for the decay of ¹³¹In, prompting us to remeasure its value. In addition to the new half lives, the high efficiency of the GRIFFIN spectrometer has enabled us to considerably expand the decay schemes of the daughter nuclei, and for example in ¹²⁸In, the analysis to date has resulted in 23 new γ-ray transitions and 15 new levels to be identified. This document is made up of an abstract and the slides of the presentation. (authors)

[en] As a continuation of our digital radiographic sensor R and D, we have developed a prototyped digital panoramic X-ray imaging system for dental applications. The imaging system consists of a slit-collimated X-ray generator with a 0.4 mm focal spot size and a 3.5 mm Al filtration, a linear-array typed CMOS imager with a 48x48 μm² pixel size and a 128 (in the scan direction)x3072 (in the vertical direction) pixel format, a series of microstep motors for the precise motion control of the imaging system, and the designed sequences for the motion control and pixel readout required to make a specific plane of interest (POI) to be focused. With the several test phantoms we designed, we obtained useful digital panoramic X-ray images by moving the X-ray generator and the CMOS imager along a continuously sliding rotational center. In this study, we demonstrated that the prototype system can be applicable to any shaped POI or multi-POIs simultaneously to be focused, provided that adequate sequences for motion control and pixel readout are designed. We expect that the imaging system will be useful for our ongoing applications of dental panoramic radiography and nondestructive testing.

No abstract available

[en] Purpose: Positron Emission Tomography (PET) is one of the most advanced medical imaging techniques in the world. The traditional practical image reconstruction algorithm of PET is Filtered- Backproiecfion (FBP). The iterative Methods based on statistical model and Least- Square principle were usually used in research stage, for their slow convergent speeds. Recently a new approach-- Ordered Subsets Expectation Maximization (OS-EM) has been used in clinic nuclear tomography, which can greatly reduce the computing time while maintaining the better' spatial resolution of the well-known Maximum Likelihood Expectation Maximization (ML-EM)iterative reconstruction method. The advantage of OS-EM over ML-EM is due to the usage of' the Ordered Subsets technology (OS), which provides a speedup factor of about L (the number of subsets). In principle, OS technology can be used in all iterative image algorithms. In our work, the Ordered Subsets Least Square (OS-LS) was introduced, and the reconstructed results were compared with OS-EM both by simulated data and real PET data. Methods: 64 x 64 Jaszczak-like model was constructed, with maximum 70 and minimum 10, see Fig l(a), 64-bin by 32-angle sinogram was simulated. And the real PET transmission sonogram data (160*192 in size) of a thorax phantom was also used to demonstrate the accelerating effect of OS in OS-EM and OS-LS. When the number of subset L equals to 1, OS-EM and OS-LS reduce to the traditional ML-EM and LS respectively. Results: The reconstructed images by 1 iteration OS-EM and OS-LS are shown in Fig1(b-e) with From Fig 1, we see the accelerating effect of OS is obvious both in OS-EM and OS-LS, and the image reconstructed by OS-EM is still better than that of OS-LS with less noise. The image reconstructed by OS-EM is still better than that of OS-LS with less noise Fig 2 shows the reconstructed images of a thorax phantom (128*128 in size) by OS-EM and OS-LS, of a real PET transmission sinogram, which was the projection data of one section of a thorax phantom. The FBP reconstructed image (no smooth window) is also given in Fig 2 to be compared with. The OS-EM and OS-LS computed in one iteration with L=t,8 subsets respectively. Conclusions: From the results above, we see the accelerating effect of OS is obvious both in OS-EM and OS-LS, and the image reconstructed by OS-EM has less noise, the quality of images is slightly better than that of OS-LS. Using P4(1.8G) computer, a 128*128 thorax phantom slice is reconstructed within 0.7 second, so in less than 1 minute, all 63 slices in a PET acquisition frame can be reconstructed in one iteration with suitable L, by both OS-EM and OS-LS. (authors)

[en] Beta spectra have been measured and total β-decay energies have been deduced for strongly neutron-rich indium isotopes. Mass separated sources were produced at the OSIRIS on-line separator at Studsvik. By applying β-γ coincidence methods, Qsub(β)-values were determined for isomers of ^120-129In. For these nuclei, the atomic mass excess could be derived, allowing the comparison of masses of neutron-rich unstable nuclei with predictions from mass formulae. The mean uncertainty of the experimental mass excesses is 0.12 MeV. The precision of the mass formulae chosen for the comparison varies widely with the mean deviation ranging from 0.12 to 1.39 MeV. (Auth.)

[en] Delayed-neutron emission from mass separated heavy fission products has been studied using a sensitive neutron counter. Twelve new delayed-neutron precursors have been found, namely ¹²²Ag, ¹²³Ag, ¹²⁷In, ¹²⁸Cd (or ¹²⁸In/sub m/), ¹²⁸In, ¹²⁹In (two isomers), ¹³⁰In, ¹³¹In, ¹³²In, ¹³³Sn, and ¹³⁶Sb. The half-life determination for 11 other precursors has been improved

[en] New beta-decaying isomers in In 127 and In 129 have been identified at 1.6 and 1.9 MeV respectively. High spin isomers with half-lives in the microsecond region were seen in Sn 127 and Sn 126, verifying and extending previous results. Good agreement was found when comparing the experimental results with theoretical calculations performed. In Sn131, the position of the h_11/2 level was determined to be 65.1 ⁺- 0.3 keV, in disagreement with the previous value of 242 keV and in agreement with systematics. The structure of Sn 131 was investigated further and new levels were identified. For Sb 131, new level schemes have been obtained, differentiating between the two beta-decaying isomers of Sn 131. Investigations of As 82 lead to the determination of the relative positions of the two isomers in As 82, a new ground state assignment of 2^- and an improved level scheme of 82Se. (Author)

No abstract available

No abstract available