Design studies for a high-resolution, transportable neutron radiography/radioscopy system

A preliminary design has been developed for a high-resolution, transportable neutron radiology system (TNRS) concept. The primary system requirement is taken to be a thermal neutron flux of 10[sup 6] n/(cm[sup 2]-sec) with a L/D ratio of 100. The approach is to use an accelerator-driven neutron source, with a radiofrequency quadrupole (RFQ) as the primary accelerator component. Initial concepts for all of the major components of the system have been developed,and selected key parts have been examined further. An overview of the system design is presented, together with brief summaries of the concepts for the ion source, low energy beam transport (LEBT), RFQ, high energy beam transport (HEBT), target, moderator, collimator, image collection, power, cooling, vacuum, structure, robotics, control system, data analysis, transport vehicle, and site support. The use of trade studies for optimizing the TNRS concept are also described

RFQ-based, transportable, high-resolution, neutron radiography system concept

A preliminary design for a high-resolution transportable neutron radiography system concept has been developed. The system requirement has been taken to be a thermal neutron flux of 10{sup 6} N/(cm{sup 2}- sec) with an L/D of 100. The approach is to use an accelerator-driven neutron source, with a radiofrequency quadrupole (RFQ) as the primary accelerator component. Initial concepts for all of the major components of the system have been developed, and selected key parts have been examined further. An overview of the system design is presented, together with brief summaries of the concepts for the ion source, LEBT, RFQ, HEBT, target, moderator, collimator, image collection, power, cooling, vacuum, structure, robotics, control system, data analysis, transport vehicle, and site support. More detailed studies completed for the RFQ and moderator designs, and issues identified during the course of the work, are described

Proof-of-Principle for Immune Control of Global HIV-1 Reactivation In Vivo

Background. Emerging data relating to human immunodeficiency virus type 1 (HIV-1) cure suggest that vaccination to stimulate the host immune response, particularly cytotoxic cells, may be critical to clearing of reactivated HIV-1–infected cells. However, evidence for this approach in humans is lacking, and parameters required for a vaccine are unknown because opportunities to study HIV-1 reactivation are rare

The Argonne ACWL, a potential accelerator-based neutron source for BNCT

The CWDD (Continuous Wave Deuterium Demonstrator) accelerator was designed to accelerate 80 mA cw of D{sup {minus}} to 7.5 MeV. Most of the hardware for the first 2 MeV was installed at Argonne and major subsystems had been commissioned when program funding from the Ballistic Missile Defense Organization ended in October 1993. Renamed the Argonne Continuous Wave Linac (ACWL), we are proposing to complete it to accelerate either deuterons to 2 MeV or protons to 33.5 MeV. Equipped with a beryllium or other light-element target, it would make a potent source of neutrons (on the order of 10{sup 13} n/s) for BNCT and/or neutron radiography. Project status and proposals for turning ACWL into a neutron source are reviewed, including the results of a computational study that was carried out to design a target/moderator to produce an epithermal neutron beam for BNCT

Moderator/collimator for a proton/deuteron linac to produce a high-intensity, high-quality thermal neutron beam for neutron radiography

Reactor based high resolution neutron radiography facilities are able to deliver a well-collimated (L/D {ge}100) thermal flux of 10{sup 6} n/cm{sup 2}{center_dot}sec to an image plane. This is well in excess of that achievable with the present accelerator based systems such as sealed tube D-T sources, Van der Graaff`s, small cyclotrons, or low duty factor linacs. However, continuous wave linacs can accelerate tens of milliamperes of protons to 2.5 to 4 MeV. The MCNP code has been used to analyze target/moderator configurations that could be used with Argonne`s Continuous Wave Linac (ACWL). These analyses have shown that ACWL could be modified to generate a neutron beam that has a high intensity and is of high quality

Current drive and heating systems based on high-energy (1- to 3-MeV) negative ion beams

This paper describes a concept for a current drive system based on negative ions with beam energy > 1 MeV. Preliminary physics calculations show that the core current necessary for stability enhancement can best be achieved by beams with energy ranging from 1 to 4 MeV. Further study and experiments will better define the optimum energy. Work under way at Oak Ridge National Laboratory (ORNL) and at collaborating institutes in Canada and the Federal Republic of Germany is defining a system, its elements, a configuration and operational scenarios deemed appropriate for such devices as ITER and other future steady-state tokamaks, and the requisite research and development to provide such a system. 7 refs., 2 figs

Towards the chemometric dissection of peptide--HLA-A*0201 binding affinity: comparison of local and global QSAR models.

The affinities of 177 nonameric peptides binding to the HLA-A*0201 molecule were measured using a FACS-based MHC stabilisation assay and analysed using chemometrics. Their structures were described by global and local descriptors, QSAR models were derived by genetic algorithm, stepwise regression and PLS. The global molecular descriptors included molecular connectivity chi indices, kappa shape indices, E-state indices, molecular properties like molecular weight and log P, and three-dimensional descriptors like polarizability, surface area and volume. The local descriptors were of two types. The first used a binary string to indicate the presence of each amino acid type at each position of the peptide. The second was also position-dependent but used five z-scales to describe the main physicochemical properties of the amino acids forming the peptides. The models were developed using a representative training set of 131 peptides and validated using an independent test set of 46 peptides. It was found that the global descriptors could not explain the variance in the training set nor predict the affinities of the test set accurately. Both types of local descriptors gave QSAR models with better explained variance and predictive ability. The results suggest that, in their interactions with the MHC molecule, the peptide acts as a complicated ensemble of multiple amino acids mutually potentiating each other