[en] The contribution of G₂ cell cycle checkpoint control to ionizing radiation responses was examined in ten human tumor cell lines. Most of the delay in cell cycle progression seen in the first cell cycle following radiation exposure was due to blocks in G₂ and there were large cell line-to-cell line variations in the length of the G₂ block. Longer delays were seen in cell lines that had mutations in p53. There was a highly significant inverse correlation between the length of G₂ delay and the frequency of unrejoined chromosome breaks seen as chromosome terminal deletions in mitosis, and observation that supports the hypothesis that the signal for G₂ delay in mammalian cells is an unrejoined chromosome break. There were also an inverse correlation between the length of G₂ delay and the level of chromosome aneuploidy in each cell line, suggesting that the G₂ and mitotic spindel checkpoints may be linked to each other. Attenuation in G₂ checkpoint control was not associated with alterations in either the frequency of induced chromosome rearrangements or cell survival following radiation exposure suggesting that chromosome rearrangements, the major radiation-induced lethal lesion in tumor cells, form before cells enters G₂. Thus, agents that act solely to override G₂ arrest should produce little radiosensitization in human tumor cells

[en] Argonne National Laboratory, with support from DOE's Office of Nonproliferation and National Security, is currently developing an intelligent hand-portable sensor system. This system is designed specifically to support the intelligence community with the task of in-field sensing of nuclear proliferation and related activities. Based upon pulsed laser photo-ionization time-of-flight mass spectrometry technology, this novel sensing system is capable of quickly providing a molecular or atomic analysis of specimens. The system is capable of analyzing virtually any gas phase molecule, or molecule that can be induced into the gas phase by (for example) sample heating. This system has the unique advantages of providing unprecedented portability, excellent sensitivity, tremendous fieldability, and a high performance/cost ratio. The system will be capable of operating in a highly automated manner for on-site inspections, and easily modified for other applications such as perimeter monitoring aboard a plane or drone. The paper describes the sensing system

[en] A key difference between a d-wave and an anisotropic s-wave superconductor is the expected effect of nonmagnetic point defects on T_c. T_c of the former becomes zero whereas T_c of the latter attains a nonzero constant value beyond a critical concentration of impurities. We report the first observation that T_c of an YBCO single crystal becomes zero after 4.1% of the planar oxygens O(2,3) are displaced by 400keV electron irradiation along the c-axis. Our data therefore indicate that YBCO is a d-wave superconductor. We also report evidence of a disorder-induced superconductor-to-normal-metal transition

[en] Gamma rays from the β^- decay of 13.8-sec ¹¹Be can be used for Ge photon detector efficiency calibration at energies > 2--3 MeV that are not accessible using more conventional gamma-ray sources. ¹¹Be is generated by the ¹¹B(n,p)¹¹Be reaction using a boron oxide sample and 14-MeV neutrons from a neutron generator. The short-lived activity is carried to the detector using a pneumatic transport system. This paper describes the experimental method used and provides an example of a Ge detector efficiency calibration curve augmented by this technique

[en] Boron neutron capture therapy (BNCT) is a binary treatment modality that can selectively irradiate tumor tissue. BNCT uses drugs containing a stable isotope of boron. ¹⁰B, to sensitize tumor cells to irradiation by low energy (thermal) neutrons. The interaction of the ¹⁰B with a thermal neutron (neutron capture) causes the ¹⁰B nucleus to split, releasing an alpha particle and a lithium nucleus. These products of the ¹⁰B(n, α)⁷Li reaction are very damaging to cells but have a combined path length in tissue of approximately 14 μm, or roughly the diameter of one or two cells. Thus, most of the ionizing energy imparted to tissue is localized to ¹⁰B-loaded cells

[en] A new procedure is developed for making TEM specimens of thin film devices. In this procedure the sample is flatly polished to an overall ion-mill-ready thickness so that any point in the 2-D sample pane can be thinned to an electron-transparent thickness by subsequent ion-milling. Using this procedure, small regions of interest can be easily reached in both cross-section and plan-view samples. This is especially useful in device studies. Applications of this procedure to the study of superconductor devices yield good results. This procedure, using commercially available equipment and relatively cheap materials, is simple and easy to realize

[en] Accurate measurement of path length and path length changes versus momentum (M₅₆) are critical for maintaining minimum beam energy spread in the CEBAF (Continuous Electron Beam Accelerator Facility) accelerator at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The relative path length for each circuit of the beam (1256m) must be equal within 1.5 degrees of 1497 MHz RF phase. A relative path length measurement is made by measuring the relative phases of RF signals from a cavity that is separately excited for each pass of a 4.2 μs pulsed beam. This method distinguishes the path length to less than 0.5 path length error. The development of a VME based automated measurement system for path length and M₅₆ has contributed to faster machine setup time and has the potential for use as a feedback parameter for automated control

[en] A study of the order α_s² corrections to the Drell-Yan (non-singlet) differential cross section for incoming states of arbitrary longitudinal helicities is presented. The transverse momentum distributions, q_T, of the lepton pair are studied and the calculations of Ellis, Martinelli, and Petronzio (EMP) are extended to include polarized initial states. The authors use the MS scheme and the t'Hooft-Veltman regularization for the helicity projectors. From the results one can obtain the bulk of the totally inclusive NNLO cross section for the production of a Drell-Yan pair in the non-singlet sector by a simple integration over the virtual photon momentum. They show that in the MS scheme helicity is not conserved along the quark lines, unless a finite renormalization is done and one adapts the physical (MS_p) scheme. This aspect of the calculation is similar to the O(α_s²) polarized production of single and double photons. The spin averaged unpolarized differential cross sections agree with the EMP calculations

[en] The ultimate source of ²²²Rn to the atmosphere is, of course, ²²⁶Ra. Tracking the mobility of radium therefore is part of the story of radon flux assessment. The study of radium mobility and radon flux measurements has involved virtually all the reservoirs at the Earth's surface. These include soils, groundwaters, coastal waters and the atmosphere. The attempt to understand the mobility of radium involved the study of almost all the radium isotopes (²²⁶Ra, ²²⁸Ra, ²²⁴Ra) and the parent and daughters of these isotopes

[en] This is a brief review of the current status of radiation treatment of surface water, groundwater, wastewaters, and sewage sludges. Sources of ionizing radiation, and combination radiation methods for purification are described in some detail. Special attention is paid to pilot and industrial facilities. (author)