Measuring national capability over big science's multidisciplinarity: A case study of nuclear fusion research.

In the era of big science, countries allocate big research and development budgets to large scientific facilities that boost collaboration and research capability. A nuclear fusion device called the "tokamak" is a source of great interest for many countries because it ideally generates sustainable energy expected to solve the energy crisis in the future. Here, to explore the scientific effects of tokamaks, we map a country's research capability in nuclear fusion research with normalized revealed comparative advantage on five topical clusters-material, plasma, device, diagnostics, and simulation-detected through a dynamic topic model. Our approach captures not only the growth of China, India, and the Republic of Korea but also the decline of Canada, Japan, Sweden, and the Netherlands. Time points of their rise and fall are related to tokamak operation, highlighting the importance of large facilities in big science. The gravity model points out that two countries collaborate less in device, diagnostics, and plasma research if they have comparative advantages in different topics. This relation is a unique feature of nuclear fusion compared to other science fields. Our results can be used and extended when building national policies for big science.

Application and methodology of dissolution dynamic nuclear polarization in physical, chemical and biological contexts.

Dissolution dynamic nuclear polarization (d-DNP) is a versatile method to enhance nuclear magnetic resonance (NMR) spectroscopy. It boosts signal intensities by four to five orders of magnitude thereby providing the potential to improve and enable a plethora of applications ranging from the real-time monitoring of chemical or biological processes to metabolomics and in-cell investigations. This perspectives article highlights possible avenues for developments and applications of d-DNP in biochemical and physicochemical studies. It outlines how chemists, biologists and physicists with various fields of interest can transform and employ d-DNP as a powerful characterization method for their research.

Nuclear decay data: observations and reflections.

Decay data constitute an important feature of nuclear physics that plays a significant role in the various work programmes of members and associates of the International Committee for Radionuclide Metrology (ICRM). At the invitation of the ICRM, a review has been undertaken with the joint aims of emphasising decay-data achievements over the previous 10 years, and highlighting inadequacies that remain to be addressed in the future.

Is biomedical nuclear magnetic resonance limited by a revisitable paradigm in physics?

The history of nuclear magnetic resonance (NMR) can be divided generally into two phases: before the Second World War, molecular beam methods made it possible to detect the whole set of spins. However, these methods were destructive for the sample and had a very low precision. The publications of F. Bloch and E. Purcell in 1946 opened up a second phase for NMR with the study of condensed matter, but at the expense of an enormous loss in theoretical sensitivity. During more than half a century, the method of Bloch and Purcell, based on inductive detection of the NMR signal, has allowed many developments in biomedicine. But, curiously, this severely constraining limitation on sensitivity has not been called into question during this half-century, as if the pioneers of the pre-war period had been forgotten.

High Intensity Proton Accelerator Project in Japan (J-PARC).

The High Intensity Proton Accelerator Project, named as J-PARC, was started on 1 April 2001 at Tokai-site of JAERI. The accelerator complex of J-PARC consists of three accelerators: 400 MeV Linac, 3 GeV rapid cycle synchrotron and 50 GeV synchrotron; and four major experimental facilities: Material and Life Science Facility, Nuclear and Particle Physics Facility, Nuclear Transmutation Experiment Facility and Neutrino Facility. The outline of the J-PARC is presented with the current status of construction.

The radioisotope complex project "RIC-80" at the Petersburg Nuclear Physics Institute.

The high current cyclotron C-80 capable of producing 40-80 MeV proton beams with a current of up to 200 µA has been constructed at Petersburg Nuclear Physics Institute. One of the main goals of the C-80 is the production of a wide spectrum of medical radionuclides for diagnostics and therapy. The project development of the radioisotope complex RIC-80 (radioisotopes at the cyclotron C-80) at the beam of C-80 has been completed. The RIC-80 complex is briefly discussed in this paper. The combination of the mass-separator with the target-ion source device, available at one of the new target stations for on-line or semi on-line production of a high purity separated radioisotopes, is explored in greater detail. The results of target and ion source tests for a mass-separator method for the production of high purity radioisotopes (82)Sr and (223,224)Ra are also presented.

Variation in output with a fixed dose setting on a 4-MV linear accelerator.

Variations in the output with a fixed monitor unit setting as a function of magnetron power of a 4-MV linear accelerator has been studied. The relationship between radiation output and monitor units was found to vary by as much as 10%. The central-axis depth dose was found to remain constant within experimental error. Field flatness measurements indicated that for lower power outputs, the radiation field was less flat than for higher power outputs. A mechanism for the change in calibration is suggested based upon field flatness measurements.

Lead shielding thickness for dose reduction of 7- to 28MeV electrons.

The relative percent dose reduction by lead of 7- to 18-MeV electrons with a Siemens betatron and of 19- to 28-MeV electrons with a Sagittaire linear accelerator has been measured with a thin-wall buildup chamber for 6.3 X 6.3- and 10.5 X 10.5-cm field sizes at the chamber position for the normal treatment source-to-skin distance (SSD) of each machine. The thickness of lead necessary to attenuate the open beam by 95-98% was then determined of 7- to 28-MeV electrons. The required thickness of lead to attenuate 95% of the 7- to 28-MeV electron beam ranged from 2.3 to 18 mm for the 6.3 X 6.3-cm field and from 2.4 to 23 mm for the 10.5 X 10.5-cm field, respectively. For 98% attenuation, thicknesses from 2.6 to 25.0 mm for the 6.3 X 6.3-cm field and from 2.8 to 27.5 mm of lead for the 10.5 X 10.5-cm field were necessary.

Model for the calculation of output for elongated fields at nonstandard distances for a 25-MV betatron and for radiocobalt teletherapy units.

Output-area factors are usually provided only for square fields at one standard distance. To calculate dose for mantle, extended field, total nodal, subtotal body, and total body irradiation, output-area factors are required for a continuous range of shapes and distances. Dose rate measurements have been made for different elongation ratios at various distances with an Allis-Chalmers 25-MV betatron, an AECL Theratron-80 60Co unit, a Picker C-9 60Co unit, and a Picker C-10000 60Co unit. A model is presented that permits the extension of dose rates and area factors for square fields at one distance to elongated fields at any distance. An illustrative calculation for one of the units is given.

Real-time display of radiation field intensity distribution.

A real-time display system has been designed and tested for use with a radiation field monitor. The system uses only pulse and waveform generators, a multiplexer, and an oscilloscope. The display consists of either a three-dimensional representation of the field intensity distribution or a series of simultaneous profiles.

Betatron-Quastler era at the University of Illinois.

New accelerator technology and a gathering of physicists and doctors interested in applications to therapy in the late 1940s made possible the development of early multimegavolt betatron techniques. Dr. Henry Quastler brought experience from an actual x-ray treatment, and Dr. Lester Skaggs joined the group to extract the electron beam. Some of the collaborating students were G.D. Adams, H.W. Koch, J.S. Laughlin, L.H. Lanzl and E.F. Lanzl. The physics staff had succeeded in sealing off a vacuum tube for the betatron, and further developments involved field flattening, exposure measurements, collimation, stray electron control, phantom tests, and development of a beam peeler.

Pretransfusion blood irradiation: clinical rationale and dosimetric considerations.

The irradiation of blood before transfusion into immunosuppressed patients is an increasingly common technique used to prevent graft-versus-host disease. A technical procedure is described for the calibration of blood irradiators, including the determination of absolute dose rate and relative dose distribution over the blood volume. Results of dose rate measurements on commercially available irradiators indicate differences of +5% to -13% with manufacturer-supplied calibrations and variations in the relative dose rate over the irradiation volume from 70% to 180%. The clinical implications of these findings and the need for accurate dosimetry are discussed.

A flow calorimetric method of determining electron beam energy.

The construction of an adiabatic flow calorimeter using water as the working substance is described. It is shown that at high dose rates the heat defect due to chemical reactions in water is small (of the order of 0-3%) and that under high dose rate conditions flow calorimetry can be used as a method of measuring the energy of high intensity electron beams. Measurements made with a 15 MeV linear accelerator are reported and compared with magnetic measurements.

Ion losses in a plane-parallel ionisation chamber irradiated with a pulsed electron beam.

Saturation curves for a plane-parallel ionisation chamber have been studied in a pulsed electron beam of 5.2 MeV initial energy as a function of chamber voltage, chamber depth and charge density liberated per pulse. It is shown that, if ion losses by diffusion and by initial recombination are appropriately considered, the remaining ion losses by volume recombination can be described by Boag's theory. The constant mu in this theory has been determined to be (2.7 +/- 0.1) x 10(10) V m C-1. This value is consistent with data on charge collection characteristics obtained using the same ionisation chamber exposed to continuous radiation from beta-sources.

The saturation loss for plane parallel ionization chambers at high dose per pulse values.

The use of plane parallel ionization chambers with electron beams with high dose per pulse entails dose uncertainties due to the overestimation of the ion recombination factor, k, up to 20% if conventional dosimetric protocols are used. In this work MD-55-2 radiochromic films have been used as reference dosimeters to obtain dose to water per pulse DGAF(w) values for three Novac7 (Hitesys) electron beams of E0 = 5.8 MeV. However, the beam calibration by MD-55-2 films is time consuming and the use of plane parallel chambers is fundamental for a periodic quality control procedure. Three plane parallel chambers have been used and the general formula for the k determination has been tested using the calibration doses, DGAF(w). In particular, consistent ion recombination factors ksat(V0) (with the ion chamber polarized at V0), that follow the Boag theory, have been estimated at different dose per pulse values for the three plane parallel ionization chambers. This means that at present any ion chamber needs a specific ksat (V0) determination by using a reference dosimeter for which the response is independent of the dose rate. An accurate determination of ksat(V0), using a reference quality beam, can be used to determine the dose to water per pulse for electron beams of different quality and geometrical configuration.

The isochronous cyclotron: principles and recent developments.

The principals of a cyclotron are described. A magnetic field guides the ions in circular paths, while an electric field accelerates them. The main problem in any accelerator is not to accelerate ions, but to focus them. An isochronous cyclotron overrules the problems related to relativistic mass increase during acceleration. Harmonic operation and negative (vs positive) ion acceleration (and extraction) are explained, as they make dedicated PET cyclotrons a simple, reliable, and suitable tool. The characteristics of such PET cyclotrons are described, as well as their technical implementation. The IBA 18/9 PET cyclotron is given as an example.

Proton and heavy ion acceleration facilities for space radiation research.

The particles and energies commonly used for medium energy nuclear physics and heavy charged particle radiobiology and radiotherapy at particle accelerators are in the charge and energy range of greatest interest for space radiation health. In this article we survey some of the particle accelerator facilities in the United States and around the world that are being used for space radiation health and related research, and illustrate some of their capabilities with discussions of selected accelerator experiments applicable to the human exploration of space.

Evaluation of a low-cost automatic counting system for nuclear track detectors.

This paper describes a low-cost automatic counting system for recognising and counting microscopic track holes in plastic nuclear track detectors. The hardware includes an Olympus BH2 microscope, (manufactured by the Olympus Optical Company, Japan) a Philips resistive gate sensor (RGS) board, (manufactured by the Philips Company, Netherlands) a frame-grabber board and an IBM PC compatible. The RGS board acts like a camera, sending analog video signals of the microscope's field image to the frame-grabber, which produces a digital image with a resolution of 256 x 256 pixels and 128 grey levels in about 20 ms. This is then stored in either one of two 64K on-board RAMs for processing by the PC. The software is menu-driven and allows image grabbing, saving, loading and processing. The image processing can be divided into three parts namely: segmentation, speckle elimination and the removal of ill-formed track holes. In this paper we will present the results of testing the system with sample images obtained from CR-39 plastic nuclear track detectors. The limitations of the system for counting track holes on these detectors will be discussed.

[Experience in the use of synchrotron radiation for the x-ray study of biopolymers]. / Opyt ispol'zovaniia sinkhrotronnogo izlucheniia dlia rentgenograficheskogo issledovaniia biopolimerov

The results of methodical work, carried out on the sources of synchrotron radiation (SR) with the aim of using SR as a powerful source of X-rays for studying biopolymer structure, are presented. The questions of monochromatization are considered. The technique designed for photoregistration of diffraction patterns within the wide range of scattering angles is described. X-ray diffraction patterns of feather ceratin, collagen and striated muscle are obtained with exposure periods ten times less than those in the case of X-ray tubes. The high resolution of diffraction lines, the absence of parasitic phone and the presence of reflections within the wide range of scattering angles are characteristic of these patterns.