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Neutron-induced reactions are studied at the neutron time-of-flight facility n_TOF at CERN. The facility uses 6 similar to ns wide pulses of 20 GeV/c protons impinging on a lead spallation target. The large neutron energy range and the high instantaneous neutron flux combined with high resolution are among the key characteristics of the facility. After a first phase of data taking during the period 2001-2004, the facility has been refurbished with an upgraded spallation target and cooling system for a second phase of data taking which started in 2009. Since 2010, the experimental area at 185 m where the neutron beam arrives, has been modified into a worksector of type A, allowing the extension of the physics program to include neutron-induced reactions on radioactive isotopes

The residual implanted dose of ultra-shallow B+ implants in Ge was characterized using elastic recoil detection and was determined to correlate well with simulations with a dose loss of 23% due to ion backscattering for 2 keV implants in Ge. The electrical characterization of ultra-shallow B+ implants at 2 keV to a dose of 5.0×1014 cm-2 at beam currents ranging from 0.4 to 6.4 mA has been studied using micro Hall effect measurements after annealing at 400˚C for 60 s. It has been shown that the sheet number increases with beam current across the investigated range with electrical activation being 76% higher at 6.4 mA as compared to 0.4mA. However, at 6.4 mA, the electrically active fraction remained low at 11.4%. Structural characterization revealed that the implanted region remained crystalline and amorphization is not able to explain the increased activation. The results suggest the presence of a stable B:Ge cluster whose formation is altered by point defect recombination during high flux implantation which results in increased B activation.

Individual charged particles could be trapped and confined by the combined radio‐frequency and DC quadrupole electric field of an aqueous Paul trap. Viscosity of water improves confinement and extends the range of the trap parameters which characterize the stability of the trap. Electrolyte, if present in aqueous solution, may screen the charged particle and thus partially or fully suppress electrophoretic interaction with the applied filed, possibly reducing it to a generally much weaker dielectrophoretic interaction with an induced dipole. Applying molecular dynamics simulation we show that the quadrupole field has a different effect at the electrolyte ions and at much heavier charged particle, effectively eliminating the screening by electrolyte ions and reinstating the electrophoretic confinement.

This work demonstrates that a holmium doped chalcogenide glass waveguide can be fabricated by ultralow dose swift ion implantation method. More than three modes exist in the waveguide at the wavelength of 632.8 nm and the refractive index profile is reconstructed. The near‐field pattern of the transmitted light is obtained and the propagation loss of the waveguide is about 4.0 dB/cm.

Intense neutron sources are essential for cargo inspection for a broad range of threats from explosives, to contraband, to nuclear materials and especially SNM (Special Nuclear Materials). To be effective over a wide range of cargo materials, in particular for hydrogenous cargo such as food, and to offer practical inspection times, the neutron source must be very strong, typically >1010 neutrons per second. Unfortunately there are currently no reasonably compact and economical neutron generators with the required intensities. The insufficiency and inadequacy of intense neutron sources are especially conspicuous in the ≤2.5 MeV range (low voltage (d,D) generator). This energy range is needed if the strong signature of prompt fission neutrons (≈3 per fission) is to be detected and discerned from the numerous source neutrons. The photonuclear reactions of x‐rays from commercial linacs in appropriate converters can provide ample intensities of neutrons. These converters have a very low (γ,n) energy threshold: 1.67 MeV for beryllium and 2.23 MeV for deuterium. The intense x‐ray beams provided by commercial x‐ray systems, more than compensate for the relatively low (γ,n) cross‐sections which are in the milli‐barn range. The choice of converter material, the geometrical shape, dimensions and location relative to the x‐ray source, determine the efficiency of the neutron conversion. For electron accelerators with less than 10 MeV, the preferred converters, Be and D2O, are also very good neutron moderators. Thus, while increasing the converters’ thickness leads to an increase in the overall neutron yield, this causes the softening of the neutron spectrum, which reduces the neutron penetration especially in hydrogenous cargos. Photoneutron sources can be optimized to meet specific needs such as maximum fission signals in various cargo materials of interest. Efficient photoneutron sources with different energy spectra were investigated. Conversion efficiency of more than 10‐4 neutron per 9 MeV electron yielding neutron intensities of more than 1011 n/s for commercial 100 μAmp electron accelerators has been modeled and designed. The simulation was validated in laboratory experiments using small Be and D2O converters.

To minimize the dose applied to the specimens during imaging in a MeV ion microbeam we have investigated new concepts that allow collection of images with multi‐resolution support. To test the concept, a set of reference PIXE microbeam images with well‐characterised noise were segmented using both a direct down‐sampling technique and wavelet decomposition. The results show both techniques could be used to select fields of view with

As the semiconductor industry continues to show more interest in the photovoltaic market, cheaper and readily integrable methods of silicon solar cell production are desired. One of these methods—ion implantation—is well‐developed and optimized in all commercial semiconductor fabrication facilities. Here we have developed a silicon surface texturing technique predicated upon the phenomenon of surface blistering of H‐implanted silicon, using only ion implantation and thermal annealing. We find that following the H implant with a second, heavier implant markedly enhances the surface blistering, causing large trenches that act as a surface texturing of c‐Si. We have found that this method reduces total broadband Si reflectance from 35% to below 5percent;. In addition, we have used Rutherford backscattering/channeling measurements investigate the effect of ion implantation on the crystallinity of the sample. The data suggests that implantation‐induced lattice damage is recovered upon annealing, reproducing the original monocrystalline structure in the previously amorphized region, while at the same time retaining the textured surface.

A periodic array of striped nanoscopic domains, embedded in the epitaxially grown Ni layer, was formed after thermal annealing of the Ni/Ni+C60/C60/Ni thin multilayer sequence deposited on the MgO(001) monocrystal. The composite was annealed in 100 °C/1 hr increments in the range of 200–600 °C, and the structural evolution of the composite was analyzed mainly by Rutherford Backscattering and Scanning Electron Microscopy. The periodic system of the stripes was revealed after annealing at 600 °C. The possible mechanism of the domain formation is suggested as follows: temperatures below 500 °C incite diffusion (and consecutive disintegration) of the C60 molecules; temperatures above 500 °C induce forceful intermixing of the upper Ni/Ni+C60/C60 layers; due to the pronounced immiscibility of the Ni and C (C60) components the process of the phase separation is triggered. In the confined crystalline matrix of the buffer Ni layer the separation proceeds coordinately according to the Ni lattice template ‐ the stri...

This paper describes industrial charged particle beamline technologies and design approaches. Beamlines accommodate myriad constraints in the radioisotope production, electron beam processing, and ion implantation market segments, and some very strange yet interesting solutions result. In this paper, a detailed look at a particular injection beamline solution gives some sense of the complexity of research and development required, and the sophistication of the beamline solutions that are utilized. A brief review of beamline applications in each industrial segment follows.

Idaho National Laboratory is experimenting with electrical neutron generators, as potential replacements for californium‐252 radioisotopic neutron sources in its PINS prompt gamma‐ray neutron activation analysis (PGNAA) system for the identification of military chemical warfare agents and explosives. In addition to neutron output, we have recently measured the x‐ray output of the Thermo Scientific P385 deuterium‐deuterium neutron generator. X rays are a normal byproduct from neutron generators, but depending on their intensity and energy, x rays can interfere with gamma rays from the object under test, increase gamma‐spectrometer dead time, and reduce PGNAA system throughput. The P385 x‐ray energy spectrum was measured with a high‐purity germanium (HPGe) detector, and a broad peak is evident at about 70 keV. To identify the source of the x rays within the neutron generator assembly, it was scanned by collimated scintillation detectors along its long axis. At the strongest x‐ray emission points, the generator also was rotated 60° between measurements. The scans show the primary source of x‐ray emission from the P385 neutron generator is an area 60 mm from the neutron production target, in the vicinity of the ion source. Rotation of the neutron generator did not significantly alter the x‐ray count rate, and its x‐ray emission appears to be axially symmetric. A thin lead shield, 3.2 mm (1/8 inch) thick, reduced the 70‐keV generator x rays to negligible levels.

The Nuclear Science and Engineering Research Center (NSERC), a Defense Threat Reduction Agency (DTRA) office located at the United States Military Academy (USMA), sponsors and manages cadet and faculty research in support of DTRA objectives. The NSERC has created an experimental pyroelectric crystal accelerator program to enhance undergraduate education at USMA in the Department of Physics and Nuclear Engineering. This program provides cadets with hands‐on experience in designing their own experiments using an inexpensive tabletop accelerator. This device uses pyroelectric crystals to ionize and accelerate gas ions to energies of ∼100 keV. Within the next year, cadets and faculty at USMA will use this device to create neutrons through the deuterium‐deuterium (D‐D) fusion process, effectively creating a compact, portable neutron generator. The double crystal pyroelectric accelerator will also be used by students to investigate neutron, x‐ray, and ion spectroscopy.

A large number of wood and bark samples have been analysed utilizing particle‐induced X‐ray emission (PIXE) and particle‐induced gamma‐ray emission (PIGE) techniques. Samples of common tree species like Scots Pine, Norway Spruce and birch were collected from a large number of sites in Southern and Southwestern Finland. Some of the samples were from a heavily polluted area in the vicinity of a copper‐nickel smelter. The samples were dry ashed at 550 °C for the removal of the organic matrix in order to increase the analytical sensitivity of the method. The sensitivity was enhanced by a factor of 50 for wood and slightly less for bark. The ashed samples were pressed into pellets and irradiated as thick targets with a millimetre‐sized proton beam. By including the ashing procedure in the method, the statistical dispersion due to elemental heterogeneities in wood material could be reduced. As a by‐product, information about the elemental composition of ashes was obtained. By comparing the concentration of an e...

We report our recent progress using a high-power, picosecond CO2 laser for Thomson scattering and ion acceleration experiments. These experiments capitalize on certain advantages of long-wavelength CO2 lasers, such as their high number of photons per energy unit and beneficial wavelength- scaling of the electrons' ponderomotive energy and critical plasma frequency. High X-ray fluxes produced in the interactions of the counter-propagating laser- and electron-beams for obtaining single-shot, high-contrast images of biological objects. The laser, focused on a hydrogen jet, generated a monoenergetic proton beam via the radiation-pressure mechanism. The energy of protons produced by this method scales linearly with the laser's intensity. We present a plan for scaling the process into the range of 100- MeV proton energy via upgrading the CO2 laser. This development will enable an advance to the laser-driven proton cancer therapy.

Positron annihilation spectroscopy coupled with a variable mono‐energy positron beam has been applied to study nanoscale polymeric nanocomposites. New information about multilayer depth profiles and structures, interfacial free‐volume and open space properties have been obtained in polystyrene/carbon nano fiber composites. The S parameter in Doppler Broadening Energy Spectra combined slow positron beam is used to quantitatively represent the free volume, open spaces, and interactions in the interface between polystyrene matrix and carbon nanofibers.

This study demonstrates a new method of radioisotope labeling of ultra-high molecular weight polyethylene inserts in prosthetic joints for wear studies. The radioisotopes {sup 97}Ru, {sup 100}Pd, {sup 100}Rh, and {sup 101m}Rh are produced in fusion evaporation reactions induced by {sup 12}C ions in a {sup 92}Zr target foil. The fusion products recoil-implant into ultra-high molecular weight polyethylene plugs, machined to fit into the surface of the inserts. During laboratory simulations of the joint motion, a wear rate of the labeled polyethylene may be measured and the pathways of wear debris particles can be traced by detecting characteristic gamma-rays. The concentration profiles of the radioisotopes extend effectively uniformly from the polyethylene surface to a depth of about 4 {mu}m. The multiplicity of labeling and the use of several gamma-ray lines aids with avoiding systematic measurement uncertainties. Two polyethylene plugs were labeled and one was fitted into the surface of the tibial insert of a knee prosthesis, which had been worn in. Actuation over close to 100,000 cycles with a 900 N axial load and a 24 deg. flexion angle removed (14{+-}1)% of the gamma-ray activity from the plug. Most of this activity dispersed into the serum lubricant identifying this asmore » the important debris pathway. Less than 1% activity was transferred to the femoral component of the prosthesis and the measured activity on the tibial tray was insignificant. Assuming uniform wear across the superior surface of the insert, a wear rate of (12{+-}3) mm{sup 3}/Megacycle was determined. This is consistent with wear rate measurements under similar conditions using other techniques.« less

The present contribution addresses Si nanocrystal (NC) formation by conventional ion implantation into the gate oxide and by a non‐conventional IBS approach of ion beam mixing of SiO2/Si interfaces in thin gate oxides, with special emphasis on well‐controlled size and position tailoring. The two approaches will be compared and related technological challenges discussed. Compared to conventional Si NC synthesis by Si+ ion implantation into the gate oxide, we take advantage of the self‐alignment ion beam mixing process, i.e., the Si NCs are formed in SiO2 at a well‐controlled small distance of ∼2 nm from the Si/SiO2 interfaces. The technical applications in non‐volatile nanocrystal memories and in light emitting field‐effect transistors (LEFET) are demonstrated.

Active neutron interrogation has been used as a technique for the detection and identification of special nuclear material (SNM) for both proposed and field‐tested systems. Idaho National Laboratory (INL) has been studying this technique for systems ranging from small systems employing portable electronic neutron generators to larger systems employing linear accelerators as high‐energy photon sources for assessment of vehicles and cargo. In order to assess the feasibility of new systems, INL has undertaken a campaign of Monte Carlo simulations of the response of a variety of masses of SNM in multiple shielding configurations to a pulsed neutron source using the MCNPX code, with emphasis on the neutron and photon response of the system as a function of time after the initial neutron pulse. We present here some preliminary results from these calculations.

Japan Proton Accelerator Research Complex (J‐PARC) will be one of the highest intensity proton accelerators in the world aiming to realize 1 MW class of the beam power. The accelerator consists of a 400‐MeV linac, a 3‐GeV rapid‐cycling synchrotron (RCS) and a main ring synchrotron (MR), and the accelerated beam is applied to several experimental facilities. The linac, which is the injector for the RCS, has about 50 cavity modules to accelerate the beam up to 400 MeV. The acceleration field error in all of them should be within ±1% in amplitude and ±1 degree in phase because the momentum spread of the RCS injection beam is required to be within 0.1%. For the cavity field stabilization, a high‐stable optical signal distribution system is used as the RF reference, and sophisticated digital feedback and feed‐forward system is working well in the low level RF control system. Consequently the providing beam to the RCS is very stable, and the beam commissioning and the experiments of the application facilities h...

Using certified multi‐element reference materials for instrumental analyses one frequently is confronted with the embarrassing fact that the concentration of some desired elements are not given in the respective certificate, nonetheless are detectable, e.g. by photon activation analysis (PAA). However, these elements might be determinable with sufficient quality of the results using scaling parameters and the well‐known quantities of a reference element within the reference material itself. Scaling parameters include: activation threshold energy, Giant Dipole Resonance (GDR) peak and endpoint energy of the bremsstrahlung continuum; integrated photo‐nuclear cross sections for the isotopes of the reference element; bremsstrahlung continuum integral; target thickness; photon flux density. Photo‐nuclear cross sections from the unreferenced elements must be known, too. With these quantities, the integral was obtained for both the known and unknown elements resulting in an inference of the concentration of the ...

SAIC’s development of VACIS™ provides useful “lessons learned” in bridging the gap from an idea to a security or contraband detection product. From a gamma densitometer idea for solving a specific Customs Service (CS) requirement (detection of drugs in near‐empty tanker trucks) in mid‐1990’s, SAIC developed a broad line of vehicle and cargo inspections systems (over 500 systems deployed to date) based on a gamma‐ray radiographic imaging technique. This paper analyzes the reasons for the successful development of VACIS and attempts to identify “lessons learned” useful for future security and contraband detection product developments.

Amyloid plaques and neurofibrillary tangles are hallmarks of Alzheimer’s disease (AD). Advances in development of imaging agents have focused on targeting amyloid plaques. Notable success has been the development of C‐11 labeled PIB (Pittsburgh Compound) and a number of studies have demonstrated the utility of this agent. However, the short half life of C‐11 (t1/2: 20 min), is a limitation, thus has prompted the development of F‐18 labeled agents. Most of these agents are derivatives of amyloid binding dyes; Congo red and Thioflavin. Some of these agents are in clinical trials with encouraging results. We have been exploring new class of agents based on 8‐hydroxy quinoline, a weak metal chelator, targeting elevated levels of metals in plaques. Iodine‐123 labeled clioquinol showed affinity for amyloid plaques however, it had limited brain uptake and was not successful in imaging in intact animals and humans. We have been successful in synthesizing F‐18 labeled 8‐hydroxy quinoline. Small animal PET/CT imaging studies with this agent showed high (7–10% ID/g), rapid brain uptake and fast washout of the agent from normal mice brains and delayed washout from transgenic Alzheimer’s mice. These promising results encouraged us in further evaluation of this class of compounds for imaging AD plaques.

Barnes‐Jewish Hospital is on the verge of offering proton radiation therapy to its patients. Those treatments will be delivered from the first Monarch 250, a state‐of‐the‐art cyclotron produced by Still River Systems, Inc., Littleton, MA. The accelerator is the world’s first superconducting synchrocyclotron, with a field‐strength of 10 tesla, providing the smallest accelerator for high‐energy protons currently available. On May 14, 2010 it was announced that the first production unit had successfully extracted 250 MeV protons. That unit is scheduled for delivery to the Siteman Cancer Center, an NCI‐designated Comprehensive Cancer Center at Washington University School of Medicine. At a weight of 20 tons and with a diameter of less than 2 meters the compact cyclotron will be mounted on a gantry, another first for proton therapy systems. The single‐energy system includes 3 contoured scatterers and 14 different range modulators to provide 24 distinct beam delivery configurations. This allows proton fields up to 25 cm in diameter, with a maximum range from 5.5 to 32 cm and spread‐out‐Bragg‐peak extent up to 20 cm. Monte Carlo simulations have been run using MCNPX to simulate the clinical beam properties. Those calculations have been used to commission a commercial treatment planning system prior to final clinical measurements. MCNPX was also used to calculate the neutron background generated by protons in the scattering system and patient. Additional details of the facility and current status will be presented.

There is an increasingly recognized need for people trained in a broad range of applied nuclear science techniques, indicated by reports from the American Physical Society and elsewhere. Anecdotal evidence suggests that opportunities for hands‐on training with small particle accelerators have diminished in the US, as development programs established in the 1960’s and 1970’s have been decommissioned over recent decades. Despite the reduced interest in the use of low energy accelerators in fundamental research, these machines can offer a powerful platform for bringing unique training opportunities to the undergraduate curriculum in nuclear physics, engineering and technology. We report here on the new MSU Applied Nuclear Science Lab, centered around the rebuild of an AN400 electrostatic accelerator. This machine is run entirely by undergraduate students under faculty supervision, allowing a great deal of freedom in its use without restrictions from graduate or external project demands.

We present experimental studies of the transmission of slow 4.5 keV Ar9+ ions through a single cylindrical‐shaped glass capillary of macroscopic dimension with large aspect ratio. We find stable transmission of a micrometer‐scale beam with considerable intensity after a charge‐up phase, in which a self‐organized process leads to the formation of a guiding electric field. We show the time evolution of the transmitted intensity through the sample for various capillary tilt angles.

Preliminary results are presented for the use of an auxiliary radiofrequency (rf) excitation voltage in combination with a high purity, high voltage rf generator to perform dipole excitation within a high precision Paul ion trap. These results show the effects of the excitation frequency over a continuous frequency range on the resultant mass spectra from the Paul trap with particular emphasis on ion ejection times, ion signal intensity, and peak shapes. Ion ejection times are found to decrease continuously with variations in dipole frequency about several resonant values and show remarkable symmetries. Signal intensities vary in a complex fashion with numerous resonant features and are driven to zero at specific frequency values. Observed intensity variations depict dipole excitations that target ions of all masses as well as individual masses. Substantial increases in mass resolution are obtained with resolving powers for nitrogen increasing from 114 to 325.

Permanent magnet microwave-driven neutron generators have been developed at Lawrence Berkeley National Laboratory. The 2.45 GHz microwave signal is directly coupled into the plasma chamber via a microwave window. Plasma is confined in an axial magnetic field produced by the permanent magnets surrounding the plasma chamber. The source chamber is made of aluminum with a diameter of 4 cm and length of 5 cm. A stack of five alumina discs, which are 3 cm in diameter and total length of 3 cm, works as microwave window. Three permanent ring magnets are used to generate the axial magnetic field required for the microwave ion source. Both hydrogen and deuterium plasma have been successfully ignited. With 330W of microwave power, source chamber pressure of 5 mTorr, and an extraction aperture of 2 mm in diameter, the deuterium ion beam measured on the target was approximately 2.5 mA. Over 90% of the ions are atomic. With the ion source at ground potential and titanium target at -40 kV, the analysis of the activated gold foil and calibrated neutron dose monitor both indicated that roughly 10{sup 7} n/s of D-D neutrons have been produced. The D-D neutron yield can be easily scaled up tomore » 10{sup 8} n/s when the titanium target is biased at -100 kV.« less

MOS capacitors were fabricated on an n‐type 6H‐SiC epitaxial layer, and charge induced in the nMOS capacitors by 15 MeV oxygen ion microbeams was measured using Transient Ion Beam Induced Current (TIBIC). The peak amplitude of TIBIC signals decreases and the fall time increases with increasing number of incident ions. The TIBIC signal peak value can be refreshed to its original value by applying a forward bias of +1 V to the oxide electrode. Since the values of the effective bias applied to gate oxide are changed by the charge state of deep hole traps, the decrease and refreshment of TIBIC peak can be interpreted in terms of change in the effective gate bias due to charge trapping and recombination by deep hole traps, respectively.

A comprehensive model has been developed to characterize and optimize the detection of Bremsstrahlung x‐ray induced fission signatures from nuclear materials hidden in cargo containers. An effective active interrogation system should not only induce a large number of fission events but also efficiently detect their signatures. The proposed scanning system utilizes a 9‐MV commercially available linear accelerator and the detection of strong fission signals i.e. delayed gamma rays and prompt neutrons. Because the scanning system is complex and the cargo containers are large and often highly attenuating, the simulation method segments the model into several physical steps, representing each change of radiation particle. Each approximation is carried‐out separately, resulting in a major reduction in computational time and a significant improvement in tally statistics. The model investigates the effect on the fission rate and detection rate by various cargo types, densities and distributions. Hydrogenous and metallic cargos, homogeneous and heterogeneous, as well as various locations of the nuclear material inside the cargo container were studied. We will show that for the photofission‐based interrogation system simulation, the final results are not only in good agreement with a full, single‐step simulation but also with experimental results, further validating the full‐system simulation.

The linear polarization of bremsstrahlung radiation emitted in collisions of spin‐polarized and unpolarized electrons with carbon and gold targets has been measured for an incident kinetic energy of 100 keV. We present preliminary results for the degree of linear polarization for incident unpolarized electrons as a function of bremsstrahlung photon energy.

Carbon ion radiotherapy for the first patient at Gunma University Heavy Ion Medical Center (GHMC) was initiated in March of 2010. The major specifications of the facility were determined based on the experience of clinical treatments at National Institute of Radiological Sciences (NIRS). The currently indicated sites of cancer treatment at GHMC are lung, prostate, head and neck, liver, rectum, bone and soft tissue. In order to evaluate the potential need for treatment in the region including Gunma prefecture and the adjacent 4 prefectures, an estimation model was constructed based on the Japanese cancer registration system, regular structure surveys by the Cancer Societies, and published articles on each cancer type. Carbon ion RT was potentially indicated for 8,085 patients and realistically for 1,527 patients, corresponding to 10% and 2% of the newly diagnosed cancer patients in the region. Prostate cancer (541 patients) followed by lung cancer (436 patients), and liver cancer (313 patients) were the most commonly diagnosed cancers.

Activity measurements on sediment samples for trapped‐charge geological dating using gamma‐ray spectroscopy are an important verification of the field‐site dose rate determination. Furthermore gamma‐ray spectroscopy can check if the natural decay series are in secular equilibrium which is a crucial assumption in such dating. Typically the activities of leading members of the Thorium and Uranium decay series are measured, which requires Germanium detectors with thin windows and good energy resolution in order to effectively detect the associated low energy gamma‐rays. Such equipment is not always readily available. The potential of conventional Germanium detectors with thick entrance window has been explored towards routine gamma‐ray spectroscopy of sediment samples using higher energy gamma‐rays. Alternative isotopes, such as Ac‐228 and Pb‐212 for the Thorium series, and Pa‐234m, Ra‐226 and Bi‐214 for the Uranium series, have been measured in order to determine the mass‐specific activity for the respective series and possibly provide a check of secular equilibrium. In addition to measurements of the K‐40 activity, with the alternative approach, the activities of both decay series can be accurately determined. The secular equilibrium condition may be tested for the Thorium series. Measurement accuracy for Pa‐234m is, however, not sufficient to permit also a reliable check of equilibrium for the Uranium series.

The material requirements for plasma‐facing components in a nuclear fusion reactor are some of the strictest and most challenging facing us today. These materials are simultaneously exposed to extreme heat loads (20 MW/m2 steady‐state, 1 GW/m2 in millisecond transients) and particle fluxes (>1024 m−2 s−1) while also undergoing high neutron irradiation (1018 neutrons/m2 s). At the Cambridge Laboratory of Accelerator Studies of Surfaces (CLASS), many of the most important issues in plasma‐surface interaction research, such as plasma‐driven material erosion and deposition, material transport and irradiation and hydrogenic retention are investigated with the use of a 1.7 MV tandem ion accelerator. Ion‐Beam Analysis (IBA) is used to investigate and quantify changes in materials due to plasma exposure and ion irradiation is used as a proxy for neutron irradiation to investigate plasma‐surface interactions for irradiated materials. This report will outline the capabilities and current research activities at CLASS.

The development of a new radiation effects microscopy (REM) technique is crucial as emerging semiconductor technologies demonstrate smaller feature sizes and thicker back end of line (BEOL) layers. To penetrate these materials and still deposit sufficient energy into the device to induce single event effects, high energy heavy ions are required. Ion photon emission microscopy (IPEM) is a technique that utilizes coincident photons, which are emitted from the location of each ion impact to map out regions of radiation sensitivity in integrated circuits and devices, circumventing the obstacle of focusing high‐energy heavy ions. Several versions of the IPEM have been developed and implemented at Sandia National Laboratories (SNL). One such instrument has been utilized on the microbeam line of the 6 MV tandem accelerator at SNL. Another IPEM was designed for ex‐vacu use at the 88″ cyclotron at Lawrence Berkeley National Laboratory (LBNL). Extensive engineering is involved in the development of these IPEM systems, including resolving issues with electronics, event timing, optics, phosphor selection, and mechanics. The various versions of the IPEM and the obstacles, as well as benefits associated with each will be presented. In addition, the current stage of IPEM development as a user instrument will be discussed in the context of recent results.

A time‐of‐flight spectrometer with the BigSol superconducting solenoid at Texas A&M was used to investigate the possibility to produce heavy and superheavy nuclei by using two body collisions involving heavy projectiles and targets. The reaction 197Au+232Th at 7.5 AMeV is studied in this work. Preliminary results for the yields of heavy nuclei are presented.

Whereas our understanding of total cross sections for ionization and capture processes in ion‐atom collisions is widely viewed as having arrived at a state of adequate maturity, the same cannot be said at all about the dynamics of collisions, multi‐electron processes or the electron continua (in target and projectile) which are at the origin of total cross sections. We depict how these processes can be studied favourably in storage ring environments. We present examples of resonant and non‐resonant electron transfer processes, radiative and non‐radiative. This is elucidated via the relation of the electron nucleus bremsstrahlung at the high energy tip of the bremsstrahlung spectrum to the radiative electron capture cusp (RECC) and a new approach to determining molecular orbital binding energies in superheavy quasi‐molecules in resonant KK charge transfer.

225Ac has tremendous potential for the treatment of metastatic cancer due to the four alpha‐particles emitted during its decay to stable 209Bi. Additionally, it is one of the few alpha‐emitters being considered for clinical trials. The anticipated 225Ac demand for these trials is expected to far exceed the annual worldwide supply of approximately 1,000 mCi/yr. Consequently, the DOE Office of Science has funded investigations into accelerator‐based production of 225Ac. Existing 232Th(p,x)225Ac cross section data indicate that up to 480 mCi/day of 225Ac could be created by bombarding a thick target of natural thorium with 100 MeV protons at the Los Alamos Isotope Production Facility. To verify these predictions, experiments are underway at the Los Alamos Neutron Science Center to measure the 232Th(p,x)225Ac production cross sections for protons in the energy range 40–200 MeV, and at 800 MeV. For 800 MeV protons, preliminary results indicate that the 225Ac production cross section is 12.4±0.6 mb and the 225R...

In this paper we present and discuss a system developed in order to optimize the mass spectrometry process of an ion implanter. The system uses a PC to control and display the mass spectrum. The operator interacts with the I/O board, that interfaces with the computer and the ion implanter by a LabVIEW code. Experimental results are shown and the capabilities of the system are discussed.

Prompt fission neutrons continue to be examined as a signature for detecting the presence of fissionable material. This technique exploits the neutron energy limitations inherent with photonuclear emissions from non‐fissionable material, allowing prompt fission neutrons to be identified and engaged for detecting nuclear material. Prompt neutron signal measurements were acquired with bremsstrahlung endpoint energies of 6 MeV for 18 targets comprised of both fissionable and non‐fissionable material; delayed neutron measurements were also collected as a reference. The 238U target was also shielded with increasing thicknesses of lead or borated polyethylene to compare the resulting detection rates of the prompt and delayed fission neutron signals.

Irradiation parameters over a period of seven years have been evaluated for a radiation processing electron accelerator facility. The parameters monitored during this time were the electron beam energy, linearity of beam current, linearity of dose with the reciprocal value of the samples speed, and dose uniformity along the scanning area after a maintenance audit performed by the electron accelerator manufacturer. The electron energy was determined from the depth‐dose curve by using a two piece aluminum wedge and measuring the practical range from the obtained curves. The linearity of dose with beam current, and reciprocal value of the speed and dose uniformity along the scanning area of the electron beam were determined by measuring the dose under different beam current and cart conveyor speed conditions using film dosimetry. The results of the experiments have shown that the energy in the range from 1 to 5 MeV has not changed by more than 15% from the High Voltage setting of the machine over the evaluat...

A complete system has been simulated using experimentally obtained input parameters for the detection of special nuclear materials (SNM). A variation of the associated particle imaging (API) technique, referred to as reverse associated particle imaging detection (RAPID), has been developed in the context of detecting 5‐kg spherical samples of U‐235 in cargo. The RAPID technique allows for the interrogation of containers at neutron production rates between ∼1×108 neutrons/s and ∼3×108 neutrons/s. The merit of performance for the system is the time to detect the threat material with 95% probability of detection and 10−4 false positive rate per interrogated voxel of cargo. Detection times of 5 minutes were found for a maximally loaded cargo container uniformly filled with iron and as low as 1 second in containers loaded to ¼ of full capacity with either iron or wood. The worse case system performance, 30 minutes interrogation time, occurs for a maximally loaded container containing wood at 0.4 g/cm3.