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Cross sections for the 44Ti(alpha,p)47V reaction which significantly affects the yield of 44Ti in supernovae were measured in the energy range 5.7 MeV

Reactions with a heavy projectile incident on a light target can be used for the efficient in-flight production of secondary radioactive beams. An overview of this technique is given using data on 17F beams produced via the p(17O, 17F)n and d(16O, 17F)n reactions. With primary 16,17O beam currents of 100 pnA, intensities of up to 2×106 17F/s on target were achieved. Using this beam, the p(17F, α) 14O reaction was measured.

A method has been developed that can provide beams of many short-lived nuclei of interest in nucleosynthesis along the rp process path. With a {sup 17}F beam (T{sub 1/2}=64 s ) the excitation function of the {sup 17}F( p,thinsp{alpha}){sup 14} O reaction was measured to determine properties of excited states in {sup 18}Ne . These states influence the rate of the {sup 14}O( {alpha},thinspp){sup 17} F reaction which is important for understanding energy generation and nucleosynthesis in x-ray bursts. The present direct measurements yield a pattern of resonances and cross sections which differ substantially from previous estimates. {copyright} {ital 1999} {ital The American Physical Society}

A technique for separating and identifying reaction products from radiative capture reactions induced by radioactive ion beams has been developed. The {sup 18}F(p,{gamma}){sup 19}Ne and {sup 18}O(p,{gamma}){sup 19}F reactions have been measured in inverse kinematics by identifying the {sup 19}F and {sup 19}Ne reaction products with respect to mass and charge at forward angles in the Fragment Mass Analyzer. A total detection efficiency of 30% and a suppression factor for the incident beam relative to the (p,{gamma}) reaction products of better than 10{sup 12}:1 was achieved. Details of the detection technique, the beam monitoring procedure as well as experience in the use of polypropylene targets in experiments with radioactive beams are discussed.

The fusion-fission cross section for the system {sup 17}F+{sup 208}Pb involving the drip line nucleus {sup 17}F has been measured at energies in the vicinity of the Coulomb barrier. No enhancement of the fusion-fission yields due to breakup or to a large interaction radius was observed. {copyright} {ital 1998} {ital The American Physical Society }

The single-particle character of states outside the doubly magic (radioactive) nucleus {sup 56}Ni has been determined through a measurement of the (d,p) neutron transfer reaction using inverse kinematics. From the spectroscopic factors of the low-lying states in {sup 57}Ni , the astrophysically interesting yield for the {sup 56}Ni( p,{gamma}) reaction to the mirror nucleus {sup 57}Cu has been calculated, utilizing charge symmetry. The rate for this reaction in the temperature range typical of novae, supernovae, and x-ray bursts is found to be more than 10 times higher than previously assumed. {copyright} {ital 1998} {ital The American Physical Society}

Stripping efficiencies for Kr+, Xe+, and Pb+ beams in helium and nitrogen gas targets have been measured at energies varying between 0.8 and 2.0 MeV. The stripping yields were determined for different target densities, ranging from single-collision conditions to equilibrium. Based on these results, approximate predictions of the equilibrium charge state distributions for low velocity (v/c=0.0040–0.0060) heavy ions with 28

The contribution of the 18 F(p,γ) reaction to the production of 19 Ne which is the crucial isotope for the breakout from the hot CNO cycle into the rp process, has been investigated in experiments with 18 F beams. Measurements of the cross sections for the 18 F(p,α) 15 O and the 18 F(p,γ) 19 Ne reactions indicate that the contribution from the (p,γ) route to the formation of 19 Ne is small.

The Coulomb explosion of 173-MeV HeH{sup +} molecular ions traversing thin carbon foils has been measured for foil thicknesses ranging from 2 to 200{mu}g/cm{sup 2}. In contrast with measurements at lower energies, the energy spectra for protons observed emerging in the incident beam direction show distinct components that correspond to the partner helium ions being in charge states 0, 1, and 2. From an analysis of the variation of the yields of these components as functions of the target thickness, we extract electron-loss cross sections that are in good agreement with theoretical estimates. {open_quotes}Wake effects{close_quotes} that increase with increasing target thickness are observed as asymmetries in the yields and energy shifts for {open_quotes}backward-going{close_quotes} as compared to {open_quotes}forward-going{close_quotes} protons. {copyright} {ital 1997} {ital The American Physical Society}

An upper limit to the production of ${}^{19}\mathrm{Ne}$ through the ${}^{18}\mathrm{F}(p,\ensuremath{\gamma})$ reaction at the recently discovered $s$-wave resonance has been determined. The limit implies that in a hot stellar environment ${(T}_{9}g0.5)$ this reaction is not a significant gateway from the hot CNO cycle towards the production of heavier elements in stars.

A Viewpoint on: Production cross sections from 82 Se fragmentation as indications of shell effects in neutron-rich isotopes close to the drip-line O. B. Tarasov, M. Portillo, D. J. Morrissey, A. M. Amthor, L. Bandura, T. Baumann, D. Bazin, J. S. Berryman, B. A. Brown, G. Chubarian, N. Fukuda, A. Gade, T. N. Ginter, M. Hausmann, N. Inabe, T. Kubo, J. Pereira, B. M. Sherrill, A. Stolz, C. Sumithrarachichi, M. Thoennessen, and D. Weisshaar Phys. Rev. C 87, 054612 (2013) – Published May 20, 2013

The Argonne Tandem Linear Accelerator System (ATLAS) has been operating on a 24 hour, seven days a week schedule since the beginning of Fiscal Year 1994. Twenty-six different ion species ran during this period in 71 separate experiments. During the past year, there have been many projects undertaken to improve operation efficiency and upgrade various accelerator systems. There is also a new ECR ion source construction project underway. This paper covers, linac operation and new tuning techniques, the second generation ECR source construction project, the refrigerator system upgrade, an upgrade to the control system. Also described is a future expansion of ATLAS as an Exotic Beam Facility. (ATLAS is a world class heavy ion accelerator with an estimated value of approximately $80 million.) A concept that would utilize ATLAS as the foundation for a facility to generate and accelerate radioactive beams is briefly discussed.

An excitation function for the {sup 18}F({ital p},{alpha}){sup 15}O reaction has been measured in the energy range {ital E}{sub c.m.}=600{endash}800 keV using a radioactive {sup 18}F beam. A resonant state with a spin value of 3/2{sup +} has been found at an energy of 652 keV above threshold. This {ital l}{sub {ital p}}=0 resonance is found to dominate the astrophysical reaction rate at temperatures {ital T}{sub 9}{approx_gt}0.5. {copyright} {ital 1996 The American Physical Society.}

A detection system has been developed for experiments with radioactive beams which have considerable contamination from a stable isobar. The system uses the gas-filled magnet technique and identifies reaction products according to nuclear charge and mass with good resolution even at energies below 1 MeV/u. In a first experiment the device has been used to measure cross sections for the 18F(p, α)15O reaction in the energy range between 650 and 840 keV/u.

The fringing fields of magnets with large apertures and short lengths greatly affect ion-optical calculations. In particular, for a high magnetic field where the iron core becomes saturated, the effective lengths and shapes of the field distribution must be considered because they change with the excitation current. Precise measurement of the three-dimensional magnetic fields and the correct application of parameters in the ion-optical calculations are necessary. First we present a practical numerical method of extracting full 3D magnetic field maps of magnetic multipoles from 2D field measurements of the surface of a cylinder. Using this novel method, we extracted the distributions along the beam axis for the coefficient of the first-order quadrupole component, which is the leading term of the quadrupole components in the multipole expansion of magnetic fields and proportional to the distance from the axis. Higher order components of the 3D magnetic field can be extracted from the leading term via recursion relations. The measurements were done for many excitation current values for the large-aperture superconducting triplet quadrupole magnets (STQs) in the BigRIPS fragment separator at the RIKEN Nishina Center RI Beam Factory. These distributions were parameterized using the Enge functions to fit the fringe field shapes at all excitation current values, so that unmeasured values are interpolated. The extracted distributions depend only on the position along the beam axis, and thus the measured three-dimensional field can easily be parameterized for ion-optical calculations. We implemented these parameters in the ion-optical calculation code COSY INFINITY and realized a first-order calculation that incorporates the effect of large and varying fringe fields more accurately. We applied the calculation to determine the excitation current settings of the STQs to realize various optics modes of BigRIPS and the effectiveness of this approach has been demonstrated.

A two-stage method for generating a radioactive 18F ion beam has been developed. 18F is produced with a medical cyclotron by 11 MeV proton activation of [18O]water, then chemically processed off-line for use in a tandem accelerator ion source. Azeotropic distillation reduces the 18O component by 105, with a resulting 18O to 18F beam ratio of about 103. The average 18F− beam intensity per synthesis is 1 ppA over 120 min from a cesium vapor, sputter negative ion source (SNICS), with a peak intensity of 4.5 ppA.

For the first time the $^{18}\mathrm{F}$(p,\ensuremath{\alpha}${)}^{15}$O reaction has been studied with a $^{18}\mathrm{F}$ beam at energies which are of interest to explosive nucleosynthesis. Utilizing the gas-filled magnet technique a clean identification of the reaction products was achieved. A resonance with spin 3/${2}^{+}$ at an equivalent c.m. energy of 660 keV dominates the yield.

A direct ion plasma sputtering effect has been observed in an electron cyclotron resonance ion source and developed into a reliable and simple method for producing ion beams from some solid materials. We describe the ion sputtering technique used with the Argonne Tandem Linac Accelerator System Positive Ion Injector Electron Cyclotron Resonance ion source to produce, to date, stable beams of nickel, silver, tellurium, gold, lead, and bismuth and present the results obtained in test cases.

The Super Separator Spectrometer S3 is a device designed for experiments with the very high intensity stable ion beam of the superconducting linear accelerator of the SPIRAL2 facility. Its Physics goals cover the study of radioactive ions produced by fusion-evaporation reactions, like superheavy elements or neutron deficient nuclei close to the proton drip line, but also neutron rich nuclei produced by multi-nucleon transfer reactions as well as ion-ion atomic interactions. It is composed of a two-step separator, with a momentum achromat followed by a mass spectrometer. Superconducting multipole triplets, combining quadruple, sextuple and octupole fields, allow a combination of high transmission and mass resolution. A specific open multipole has been designed to stop the high beam power at the first momentum dispersive plane. A decay spectroscopy detection set-up or a low energy branch can be coupled to S3 for a wide range of studies.

The recently completed positive-ion injector for the heavy-ion accelerator ATLAS is a replacement for the tandem injector of the present tandem-linac system. Unlike the tandem, the new injector provides ions from the full range of the periodic table. The concept for the new injector, which consists of an ECR ion source on a voltage platform coupled to a very-low-velocity superconducting linac, introduces technical problems and uncertainties that are well beyond those encountered previously for superconducting linacs. The solution to these problems and their relationship to performance are outlined, and experience in the operation of ATLAS with its new injector is discussed.

A Positive-Ion Injector (PII) designed to enable ATLAS to accelerate all stable nuclei has been completed and successfully tested. This new injector system consists of an ECR source on a 350-kV platform coupled to a 12-MV superconducting injector linac formed with four different types of independently-phased 4-gap accelerating structures. The injector linac is configured to be optimum for the acceleration of uranium ions from 0.029 to ≈ 1.1 MeV/u. When ions with q/A > 0.1 are accelerated by PII and injected into the main ATLAS linac, CW beams with energies over 6 MeV/u can be delivered to the experimental areas. Since its completion in March 1992, PII has been tested by accelerating 30 Si 7+ , 40 Ar 11+ , 132 Xe 13+ , and 208 Pb 24+ . For all of these, transmission through the injector linac was ∼100% of the pre-bunched beam, which corresponds to ∼60% of the DC beam from the source. The accelerating fields of the superconducting resonators were somewhat greater than the design goals, and the whole system ran stably for long periods of time.

We report a measurement of the lifetime of the 2 [sup 2][ital S][sub 1/2] state in one-electron krypton and a direct determination of the branching ratio for the [ital M]1 decay of this state. The branching-ratio measurement provides a sensitive test of the relativistic corrections to the decay rate. The lifetime measurement yields (36.8[plus minus]1.4) ps and the branching ratio is found to be 0.356(15), both in good agreement with the theoretical values of 37.008 ps and 0.3643, respectively. From these measurements we also deduce the corresponding magnetic-dipole decay rate [ital A][sub [ital M]1]=9.68(55)[times]10[sup 9]s[sup [minus]1] and the two-photon decay rate [ital A][sub 2[ital E]1] =1.750(78)[times]10[sup 10] s[sup [minus]1].

A method is presented that allows the reconstruction of trajectories in particle spectrographs and the reconstructive correction of residual aberrations that otherwise limit the resolution. Using a computed or fitted high order transfer map that describes the uncorrected aberrations of the spectrograph, it is possible to calculate a map via an analytic recursion relation that allows the computation of the corrected data of interest such as reaction energy and scattering angle as well as the reconstructed trajectories in terms of position measurements in two planes near the focal plane. The technique is only limited by the accuracy of the position measurements, the incoherent spot sizes, and the accuracy of the transfer map. In practice the method can be expressed as an inversion of a nonlinear map and implemented in the differential algebraic framework. The method is applied to correct residual aberrations in the S800 spectrograph which is under construction at the National Superconducting Cyclotron Laboratory at Michigan State University and to two other high resolution spectrographs.

A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identified by using the superconducting in-flight separator BigRIPS. We observed 45 new neutron-rich isotopes: 71Mn, 73,74Fe, 76Co, 79Ni, 81,82Cu, 84,85Zn, 87Ga, 90Ge, 95Se, 98Br, 101Kr, 103Rb, 106,107Sr, 108,109Y, 111,112Zr, 114,115Nb, 115,116,117Mo, 119,120Tc, 121,122,123,124Ru, 123,124,125,126Rh, 127,128Pd, 133Cd, 138Sn, 140Sb, 143Te, 145I, 148Xe, and 152Ba.

A beam analysis device, the A1200, has been constructed at the National Superconducting Cyclotron Laboratory (NSCL) for routine cyclotron beam analysis, and separation of radioactive beams produced from projectile fragmentation. It has been in operation since October 1990. The A1200 begins the NSCL beamlines following the K1200 cyclotron, and hence can transport radioactive ions to any experimental device. Some details of the mechanical and optical designs are presented, along with a discussion of the initial operation.

Measurements of ($^{3}\mathrm{He}$,$d$) reactions can provide information on the proton widths of states that play a role in astrophysically important ($p,\ensuremath{\gamma}$) reactions. We report on the first study of the ($^{3}\mathrm{He}$,$d$) reaction in inverse kinematics with a $^{56}\mathrm{Ni}$$ ({T}_{1/2}=6.1 \mathrm{d})$ ion beam. The $Q$-value resolution of $~$ keV achieved in this experiment was sufficient to separate the transitions populating the ground state and the $1/{2}^{\ensuremath{-}}\text{\ensuremath{-}}5/{2}^{\ensuremath{-}}$ doublet at ${E}_{x}~1.1$ MeV in $^{57}\mathrm{Cu}$. Prospects for similar ($^{3}\mathrm{He}$,$d$) experiments with improved energy resolution are also discussed.

International audience; S3 (Super Separator Spectrometer) is a device designed for experiments with the very high intensity stable beams of LINAG, the superconducting linear accelerator of GANIL, which will be built in the framework of SPIRAL2. These beams can reach intensities exceeding 100pμA for lighter ions. These unprecedented intensities open new opportunities in several physics domains, e.g. super-heavy and very-heavy element properties, spectroscopy at and beyond the dripline, isomer and ground state properties, and the products of multi-nucleon transfer and deep-inelastic reactions. An international collaboration has been formed for proposing physics experiments and developing technical solutions for this new instrument. We present here the optical layout of the spectrometer and the studies of its multipole magnets.

A second order analytical and an arbitrary order numerical procedure is developed for the computation of transfer maps of energy degraders. The incorporation of the wedges into the optics of fragment separators for next-generation exotic beam facilities, their optical effects, and the optimization of their performance is studied in detail. It is shown how to place and shape the degraders in the system such that aberrations are minimized and resolving powers are maximized.

We have used the Michigan State University National Superconducting Cylcotron Laboratory A1200 radioactive beam facility and a newly designed neutron detector array to measure the first \ensuremath{\beta}-delayed neutron spectrosopy of $^{15}\mathrm{B}$ and the $^{15}\mathrm{B}$ \ensuremath{\beta}-decay branch to $^{15}\mathrm{C}$ bound states. The $^{15}\mathrm{B}$ ions were produced as projectile fragments in the interaction of an E/A=80 MeV $^{18}\mathrm{O}$ beam with a thick beryllium target. From these measurements, we deduce the $^{15}\mathrm{B}$ \ensuremath{\beta}-decay branching ratios. The results are compared with shell-model predictions carried out in the psd model space.

Angular distributions have been measured for 0{sup +}{r arrow}1{sup +} transitions with the ({sup 12}C,{sup 12}B) reaction on targets of {sup 12}C, {sup 26}Mg, {sup 54}Fe, {sup 58}Ni, and {sup 90}Zr and with the ({sup 12}C,{sup 12}N) reaction on targets of {sup 12}C and {sup 56}Fe. The bombarding energy was {ital E}/{ital A}=70 MeV, and small-angle data were obtained. A comparison of the cross sections measured for the ({sup 12}C,{sup 12}B) reaction with the results of distorted-wave-approximation calculations indicates that 0{sup +}{r arrow}1{sup +} transitions are predominantly one step at {ital E}/{ital A}=70 MeV. The calculated cross sections are generally in good agreement (to within 40% in magnitude) with the measured cross sections, and the angular distributions are well described quantitatively in many cases. A correlation between cross sections and known Gamow-Teller (GT) strengths {ital B}(GT) for the corresponding transitions has been found. This correlation, which is weakly dependent on the target mass, establishes a calibration for the reactions. It is used to determine {ital B}(GT) values of astrophysical interest for two low-lying 1{sup +} levels in {sup 56}Mn from the cross sections measured for the {sup 56}Fe({sup 12}C,{sup 12}N){sup 56}Mn reaction. The results are compared with two shell-model calculationsmore » performed to obtain {ital B}(GT) for {sup 56}Fe{r arrow}{sup 56}Mn transitions and with another calculation from the literature. Computational tests were performed to evaluate (a) the contribution to the cross sections of terms not present in nucleon-induced charge-exchange reactions and (b) the extent to which the cross sections provide a measure of GT strength.« less

A beam analysis device, the A1200, has been constructed at the National Superconducting Cyclotron Laboratory (NSCL) for routine cyclotron beam analysis. This device can also be used to separate radioactive beams produced by projectile fragmentation. Since the A1200 begins the K1200 cyclotron beam lines, radioactive ions can be delivered to any experimental device. The details of the mechanical and optical designs are presented. In addition some of the planned experiments with the separated radioactive beams are discussed.

The Super Separator Spectrometer (S3) will receive the very high intensity heavy ion beams from the LINAG accelerator of SPIRAL2. Its privileged fields of physics are the delayed study of rare nuclei and secondary reactions with exotic nuclei. The project is presently in a phase of conceptual design. It includes a rotating target to sustain the high energy deposit, a two stages separator (momentum achromat) and spectrometer (mass spectrometer). Various detection set-ups are foreseen, especially a delayed α, γ, and electron spectroscopy array and a gas catcher coupled to a low energy branch. We present here the current status of the project and its main features.

Large scale beam dynamics simulations are important to support the design and operations of an accelerator. The beam dynamics code TRACK, originally developed at Argonne National Laboratory (ANL) has become a general beam dynamics code for hadron linacs and has found wide applications worldwide. In order to combine the unique features of TRACK with large scale and fast parallel computing we have recently developed parallel version of the code: PTRACK It has been successfully benchmarked on different platforms: BG/L and Jazz at ANL, Iceberg at ARSC and Seaborg at NERSC. Large scale end-to- end simulations of the FNAL proton driver has been performed, where 100 millions particles were tracked. The actual parallel version has the potential of simulating 109 particles on 10 racks with 20,480 processors of BG/L at ANL, which will be available in 2008. This paper focus on efficient parallelization method been used in PTRACK.

To be published in Journal of the Physical Society of Japan; A search for new isotopes using in-flight fission of a 345 MeV/nucleon $^{238}$U beam has been carried out in the commissioning experiment of the next-generation in-flight radioactive beam separator BigRIPS at the RI beam factory at the RIKEN Nishina Center. Two neutron-rich palladium isotopes $^{125}$Pd and $^{126}$Pd were observed for the first time, which demonstrates the great potential of the RIKEN RI beam factory.

Next-generation high-intensity large acceptance fragment separators require a careful design due to the large high order aberrations induced by the large aperture superconducting magnets needed to collect rare isotopes obtained from a high energy primary heavy-ion beam hitting a target. In this paper we propose a fragment separator layout based on various symmetries that satisfies the baseline requirements. Analytical calculations based on symmetry theories simplify the design to numerical optimization of a basic cell with only a few magnetic elements. The insight provided by these calculations resulted in the specification of a simple layout with large acceptance, transmission, and resolution. The design method may be easily adapted to project-specific needs. The important effects of energy degraders necessary for full fragment separator design will be addressed in a future publication.

A suite of nuclear and atomic physics codes for computing a variety of quantities relevant for heavy-ions over a wide energy range passing through material were implemented in the DA-based beam optics code COSY Infinity. As extensions to COSY we also developed a limited fission model, map computation for beam-material interactions, and a hybrid map-Monte-Carlo mode that allows relatively fast and accurate fragment separator design, end-to-end modeling and simulations, and performance optimization. Some results are briefly mentioned; details will be published elsewhere.

The Office of Science of the Department of Energy is currently considering options for an advanced radioactive beam facility in the U.S which is a reduced scale version of the Rare Isotope Accelerator (RIA) project [1,2]. This facility will have unique capabilities compared with others both existing and planned elsewhere. As envisioned at ANL, the facility, called the Advanced Exotic Beam Laboratory (AEBL), would consist of a heavy-ion driver linac, a post-accelerator and experimental areas. Secondary beams of rare isotopes will be available as high quality reaccelerated or stopped beams from a gas catcher and high power ISOL targets, as well as, high energy beams following in-flight fragmentation or fission of heavy ions. The proposed design of the AEBL driver linac is a cw, fully superconducting, 833 MV linac capable of accelerating uranium ions up to 200 MeV/u and protons to 580 MeV with 400 kW beam power. An extensive research and development effort has resolved many technical issues related to the construction of the driver linac and other systems required for AEBL. This paper presents the status of planning, some options for such a facility, as well as, progress in related R&D.

The Advanced Exotic Beam Laboratory (AEBL) being developed at ANL consists of an 833 MV heavy-ion driver linac capable of producing uranium ions up to 200 MeV/u and protons to 580 MeV with 400 kW beam power. We have designed all accelerator components including a two charge state LEBT, an RFQ, a MEBT, a superconducting linac, a stripper station and chicane. We present the results of an optimized linac design and end-to-end simulations including machine errors and detailed beam loss analysis.

Next-generation facilities for the production of exotic beams require large acceptance fragment separators to separate and transmit rare isotopes. Fragment separators require energy degraders in order to achieve high purity separation of these rare species. The introduction of the degrader into an aberration-free optical design of a separator induces aberrations at the achromatic image. These may be completely eliminated by shaping the degrader appropriately. We have shown that, in order to eliminate these aberrations, some aberrations must be nonzero at the dispersive image, where the degrader is placed. A second order design with robust optics is presented.

International audience; $S^3$ (Super Separator Spectrometer) is a device proposed for experiments with the very high intensity stable beams of LINAG, the superconducting linear accelerator of GANIL, which will be built in the framework of SPIRAL2. These beams, which will provide in a first phase of SPIRAL2 ions with A/q = 3, can reach intensities exceeding 100pµA for lighter ions (A < 40 – 50) depending on the final choice of the ECR (Electron Cyclotron Resonance) ion source. These unprecedented intensities open new opportunities in several physics domains, e.g. super-heavy and very-heavy nuclei, spectroscopy at and beyond the dripline, muld-nucleon transfer and deep-inelastic reactions, isomers and ground state properties and nuclear molecular resonances. An international collaboration interested in the aforementioned physics has been formed for developing technical solutions for this new instrument.

The development of high-power beam dumps and catchers, and pre-separator layouts for proposed fragment separators of the Rare-Isotope Accelerator (RIA) Facility are important in realizing how to handle the 400 kW in the primary beam. Examples of pre-conceptual designs of the pre-separator area and components, along with examples of ongoing radiation simulations with results characterizing the secondary radiation are given. These initial studies will yield insight into the impact of the high-power dissipation on fragment separator design, remote handling concepts, nuclear safety and potential facility hazard classification, shielding design, civil construction design, component design, and material choices. Furthermore, they will provide guidance on detailed radiation analyses as designs mature.

Experiments were conducted to demonstrate the stable operation of a windowless liquid lithium target under extreme thermal loads that are equivalent to uranium beams from the proposed Rare Isotope Accelerator (RIA) driver linac. The engineering and safety issues accompanying liquid lithium systems are first discussed. The liquid metal technology knowledge base generated primarily for fast reactors, and liquid metal cooled fusion reactors, was applied to the development of these systems in a nuclear physics laboratory setting. The use of a high energy electron beam for simulating a high power uranium beam produced by the RIA driver linac is also described. Calculations were performed to obtain energy deposition profiles produced by electron beams at up to a few MeV to compare with expected uranium beam energy deposition profiles. It was concluded that an experimental simulation using a 1-MeV electron beam would be a valuable tool to assess beam-jet interaction. In the experiments, the cross section of the windowless liquid lithium target was 5 mm x 10 mm, which is a 1/3rd scale prototype target, and the velocity of the liquid lithium was varied up to 6 m/s. Thermal loads up to 20 kW within a beam spot diameter of 1mm were applied on the windowless liquid lithium target by the 1-MeV electron beam. The calculations showed that the maximum power density and total power deposited within the target, from the electron beam, was equivalent to that of a 200-kW, 400-MeV/u uranium beam. It was demonstrated that the windowless liquid lithium target flowing at velocities as low as 1.8 m/s stably operated under beam powers up to 20 kW without disruption or excessive vaporization.

The Rare‐Isotope Accelerator (RIA) facility is a top priority project in the U.S. RIA is a next generation facility for basic research with radioactive beams that utilizes both standard isotope‐separator on‐line and in‐flight fragmentation methods with novel approaches to handle high primary‐beam power and remove existing limitations in the extraction of short‐lived isotopes. A versatile primary accelerator, a 1.4‐GV, CW superconducting linac, will provide beams from protons at 1 GeV to uranium at 400 MeV/u at power levels of 400 kW. Novel features include the acceptance of two charge states of heavy ions from the ion source and the acceleration of five charge states following the stripper foils. To achieve these goals, comprehensive beam dynamics studies have been performed to optimize the design of the driver linac. Recently we have investigated the feasibility of increasing the currents of light ions to deliver megawatts of beam power. This option is entirely possible from the beam dynamics point of view. It would require higher power from the rf system, as well as, increased shielding at the beam loss points with respect to the existing baseline design. Preliminary indications of the limitations of beam power for this class of CW superconducting linac for light ion beams will be presented.

A group including many ANL Physics Division staff and ATLAS outside users has discussed possibilities for research with radioactive ion beams and prepared a working paper entitled ‘‘Concept for an Advanced Exotic Beam Facility Based on ATLAS.’’ Several subgroups have been working on issues related to ion sources and targets which could be used in the production and ionization of radionuclides with high power primary beams. Present activities include: (a) setting up an ion source test stand to measure emittances and energy spreads of ISOL‐type ion sources, (b) experiments to evaluate methods of containing liquid uranium for production targets, (c) experimental evaluation of geometries for the generation of secondary neutron beams for production of radionuclides, (d) setting up an ISOL‐type ion source at a neutron generator facility to measure fission fragment release times and efficiencies, and (e) computer simulations of an electron‐beam charge‐state amplifier to increase the charge states of 1+ secondary...

The emphasis of this article is on the common fundamentals and techniques on which the wide variety of different beam-optical devices are based. It should give the reader the necessary background to understand the principles of the actual devices described elsewhere in more advanced treatments. Along with the qualitative description of the basic building blocks of charged particle beam optics, enough selected references to monographs and research reports are given to guide the interested reader towards more in-depth studies. Relatively few references to original research papers are given, but extensive bibliographies are included in the listed review articles and textbooks. Topics introduced include: single-particle motion of charged particles in electric and magnetic fields, sources of charged particles, beam handling and transport, magnetic and electric deflection systems, aberrations of charged particle optical systems, and the mathematics of matrix methods for charged particle optical simulation. Keywords: charged particles; ions; electrons; beam optics; beam transport; magnetic spectrometers; magnetic spectrographs; mass analyzers; focussing and deflection; lenses; accelerators; aberrations; matrix optics; ion sources; ray tracing; achromatic; isochronous; phase space; emittance; space charge; brightness; perveance; Lorentz force

Targets employing refractory compounds are being developed for the rare isotope accelerator (RIA) facility to produce ion species far from stability. With the 100 kW beams proposed for the production targets, dissipation of heat becomes a challenging issue. In our two-step target design, neutrons are generated in a refractory primary target, inducing fission in the surrounding uranium carbide. The interplay of density, grain size, thermal conductivity and diffusion properties of the UC 2 needs to be well understood before fabrication. Thin samples of uranium carbide were prepared for thermal conductivity measurements using an electron beam to heat the sample and an optical pyrometer to observe the thermal radiation. Release efficiencies and independent thermal analysis on these samples are being undertaken at Oak Ridge National Laboratory (ORNL). An alternate target concept for RIA, the tilted slab approach promises to be simple with fast ion release and capable of withstanding high beam intensities while providing considerable yields via spallation. A proposed small business innovative research (SBIR) project will design a prototype tilted target, exploring the materials needed for fabrication and testing at an irradiation facility to address issues of heat transfer and stresses within the target.

At the IRIS facility (PNPI, Gatchina) on-line tests of high temperature uranium carbide targets of different density have been carried out. A number of isotopes: 58–60Mn, 113–119Ag, 119,121Cd, 119–125In, 127–132Sn, 192,196Tl, 196–199Pb, 196Bi, 197–200Po and 201,203At were produced making use of a high temperature electron bombardment ion source (see Fig. 1).