Adelphi Technology Research Articles

Proposed low-energy absolute calibration of nuclear recoils in a dual-phase noble element TPC using [formula omitted] neutron scattering kinematics

We propose a new technique for the calibration of nuclear recoils in large noble element dual-phase time projection chambers used to search for WIMP dark matter in the local galactic halo. This technique provides an insitu measurement of the low-energy nuclear recoil response of the target media using the measured scattering angle between multiple neutron interactions within the detector volume. The low-energy reach and reduced systematics of this calibration have particular significance for the low-mass WIMP sensitivity of several leading dark matter experiments. Multiple strategies for improving this calibration technique are discussed, including the creation of a new type of quasi-monoenergetic neutron source with a minimum possible peak energy of 272keV. We report results from a time-of-flight-based measurement of the neutron energy spectrum produced by an Adelphi Technology, Inc. DD108 neutron generator, confirming its suitability for the proposed nuclear recoil calibration.

Development of high flux thermal neutron generator for neutron activation analysis

The new model DD110MB neutron generator from Adelphi Technology produces thermal (<0.5eV) neutron flux that is normally achieved in a nuclear reactor or larger accelerator based systems. Thermal neutron fluxes of 3–5·107n/cm2/s are measured. This flux is achieved using four ion beams arranged concentrically around a target chamber containing a compact moderator with a central sample cylinder. Fast neutron yield of ∼2·1010n/s is created at the titanium surface of the target chamber. The thickness and material of the moderator is selected to maximize the thermal neutron flux at the center. The 2.5MeV neutrons are quickly thermalized to energies below 0.5eV and concentrated at the sample cylinder. The maximum flux of thermal neutrons at the target is achieved when approximately half of the neutrons at the sample area are thermalized. In this paper we present simulation results used to characterize performance of the neutron generator. The neutron flux can be used for neutron activation analysis (NAA) prompt gamma neutron activation analysis (PGNAA) for determining the concentrations of elements in many materials. Another envisioned use of the generator is production of radioactive isotopes. DD110MB is small enough for modest-sized laboratories and universities. Compared to nuclear reactors the DD110MB produces comparable thermal flux but provides reduced administrative and safety requirements and it can be run in pulsed mode, which is beneficial in many neutron activation techniques.

Development of a new deuterium–deuterium (D–D) neutron generator for prompt gamma-ray neutron activation analysis

A new deuterium–deuterium (D–D) neutron generator has been developed by Adelphi Technology for prompt gamma neutron activation analysis (PGNAA), neutron activation analysis (NAA), and fast neutron radiography. The generator makes an excellent fast, intermediate, and thermal neutron source for laboratories and industrial applications that require the safe production of neutrons, a small footprint, low cost, and small regulatory burden. The generator has three major components: a Radio Frequency Induction Ion Source, a Secondary Electron Shroud, and a Diode Accelerator Structure and Target. Monoenergetic neutrons (2.5MeV) are produced with a yield of 1010n/s using 25–50mA of deuterium ion beam current and 125kV of acceleration voltage. The present study characterizes the performance of the neutron generator with respect to neutron yield, neutron production efficiency, and the ionic current as a function of the acceleration voltage at various RF powers. In addition the Monte Carlo N-Particle Transport (MCNP) simulation code was used to optimize the setup with respect to thermal flux and radiation protection.

Technology and Applications of Neutron Generators Developed by Adelphi Technology, Inc

A standard product line of high yield neutron generators has been developed at Adelphi Technology Inc. The generators use the D-D fusion reaction and are driven by an ion beam supplied by a microwave ion source. Yields of up to 5×109 n/s have been achieved, which are comparable to those obtained using the more efficient D-T reaction. The microwave-driven plasma uses the electron cyclotron resonance (ECR) to produce a high plasma density for high current and high atomic ion species. These generators have an actively pumped vacuum system that allows operation at reduced pressure in the target chamber, increasing the overall system reliability. Variations of these generators have been produced to increase the yield and total flux available. Several of the generators have been enclosed in radiation shielding/moderator structures designed for customer specifications. These generators have been proven to be useful for prompt gamma neutron activation analysis (PGNAA), neutron activation analysis (NAA) and fast neutron radiography. Pulsed and continuous operation has been demonstrated. Larger thermal neutron fluxes are expected to be obtained by multiple ion beams striking a central target that is filled with moderating material. Thus these generators make excellent fast, epithermal and thermal neutron sources for laboratories and industrial applications that require neutrons with safe operation, small footprint, low cost and small regulatory burden.

The Pros and Cons of Preliminary R&D of Boron Neutron Capture Therapy Based on Compact Neutron Generators: A Plan of Collaboration

The characteristics of boron neutron capture therapy (BNCT) for cancer treatment demand, in addition to sufficient fluxes of epithermal neutrons, proper conditions of the neutron sources—compact layout, flexible operation, compatibility with hospital setting, etc. These requirements are best satisfied by compact accelerator-driven sources (CANS). We discuss the trade-offs among different CANS options and the needed R&D in order to advance BNCT to an acceptable level of practical prevalence and cancer treatment scope. We focus our attention on compact neutron generators (CNGs) which are the most compact and least expensive. We argue that the usefulness of D-D CNGs for preliminary studies, in spite of the substantial lower fluxes, can be augmented by high-performance beam-shaping assemblies and discoveries of superior 10B-containing cancer-cell seeking drugs. The plausibility of BNCT treatment of breast cancer using neutrons from a DD-109 CNG (Adelphi Technology, Inc.) is assessed by calculating the distribution of photon equivalent dose on a breast phantom using Monte-Carlo (MCNPX) simulations.

Liquefied Noble Gas Detectors for Detection of Nuclear Materials

Liquefied noble gas (LNG) detectors have already been successfully employed in areas of fundamental particle physics research due to features such as their high energy resolution, fast response times, excellent discrimination between neutron and gamma-ray interactions, and relatively low cost. Such detectors are also attractive for nonintrusive inspection for the presence of special nuclear material (SNM) in large-scale objects such as cargo containers and trucks. An effective method of interrogation involves pulsing the object being interrogated with neutrons, which induces fission in the SNM. The fission reaction promptly releases gamma rays and neutrons. This reaction can be distinguished from background through the coincidence measurement of these particles striking multiple detectors. Rapiscan Laboratories, Yale University Physics Department, and Adelphi Technology have constructed two 18-L liquid argon prototype detectors to investigate the suitability of LNG detectors in performing this form of interrogation. The pulse shape, energy resolution, time resolution, detector efficiency, and the effects of doping with xenon were measured.

Liquefied Noble Gas (LNG) detectors for detection of nuclear materials

Liquefied-noble-gas (LNG) detectors offer, in principle, very good energy resolution for both neutrons and gamma rays, fast response time (hence high-count-rate capabilities), excellent discrimination between neutrons and gamma rays, and scalability to large volumes. They do, however, need cryogenics. LNG detectors in sizes of interest for fissionable material detection in cargo are reaching a certain level of maturity because of the ongoing extensive R&}D effort in high-energy physics regarding their use in the search for dark matter and neutrinoless double beta decay. The unique properties of LNG detectors, especially those using Liquid Argon (LAr) and Liquid Xenon (LXe), call for a study to determine their suitability for Non-Intrusive Inspection (NII) for Special Nuclear Materials (SNM) and possibly for other threats in cargo.Rapiscan Systems Laboratory, Yale University Physics Department, and Adelphi Technology are collaborating in the investigation of the suitability of LAr as a scintillation material for large size inspection systems for air and maritime containers and trucks. This program studies their suitability for NII, determines their potential uses, determines what improvements in performance they offer and recommends changes to their design to further enhance their suitability. An existing 3.1 liter LAr detector (microCLEAN) at Yale University, developed for R&}D on the detection of weakly interacting massive particles (WIMPs) was employed for testing. A larger version of this detector (15 liters), more suitable for the detection of higher energy gamma rays and neutrons is being built for experimental evaluation. Results of measurements and simulations of gamma ray and neutron detection in microCLEAN and a larger detector (326 liter CL38) are presented.

New detector for use in fast neutron radiography

We have developed and tested a new detector for use in the fast neutron (FN) imaging radiography applications, which is distinct from other presently known FN imagers. Our device implements a neutron-sensitive scintillator attached to a position-sensitive photomultiplier tube, and operates in the event-by-event readout mode, acquiring energy, timing, and pulse shape information for all detected radiation events. This information is used to help separate events of FN interactions in the scintillator from the background events, caused by the electronics noise and by other types of background radiation. The detector performance for FN imaging application was tested using the D-D neutron generator, designed and manufactured by Adelphi Technology, Inc. This essentially point-like neutron source operates in continuous mode, producing up to 109 of 2.5 MeV neutrons per second. Samples made of metals, plastic, and other materials were used to measure the detector resolution, efficiency and uniformity. Results of these tests are presented and discussed. Both X and Y position resolutions of the FN imaging detector are estimated to be less than 0.5 mm (sigma). Because this detector shows the fraction-of-a-millimeter resolution desirable for most of FN applications, is capable of good neutron-background separation, and is built using radiation hard materials, we believe that it could be a good alternative to other FN imaging systems based on CCD or solid state detectors. In addition, because of its sub-nanosecond timing resolution, it is suitable for the time-of-flight energy-resolved FN imaging.

Neutron generators developed at LBNL for homeland security and imaging applications

The Plasma and Ion Source Technology Group at Lawrence Berkeley National Laboratory has developed various types of advanced neutron generators for wide range of applications. The latest developments include a T–T fusion reaction based point neutron generator for Tensor Technology Inc. for airport cargo screening and a single beam, D–D fusion based axial neutron generator for neutron imaging applications for Adelphi Technology Inc. These neutron generators utilize RF-induction discharge to ionize the deuterium/tritium gas. This discharge method provides high plasma density for high output current, high atomic species from molecular gases, long life operation and versatility for various discharge chamber geometries. Stability of the discharge allows for accurate modeling of the beam dynamics in accelerator section of these neutron generators. Current status of the neutron generator development with experimental data will be presented.