Publications (24)14.11 Total impact
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Conference Proceeding: Super cocktails for heavy ion testing
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ABSTRACT: The 4.5 MeV/nucleon heavy ion cocktail at the 88-Inch Cyclotron has been expanded by incorporating beams from solid material to fill in the linear energy transfer curve. This supercocktail is available by special request and is useful when only normal incidence between the beam and the device under test is possible or desirable.Radiation Effects Data Workshop, 2007 IEEE; 08/2007 -
Conference Proceeding: Berkeley Accelerator Space Effects (BASE) Light Ion Facility Upgrade
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ABSTRACT: The BASE light ion facility upgrades have been completed. All proton beams are now delivered to Cave 4A. New control software, a larger diameter beam window, and improved quality assurance measures have been addedRadiation Effects Data Workshop, 2006 IEEE; 08/2006 -
Article: Reexamination of the energy levels of^{15} F by^{14} O+^{1} H elastic resonance scattering
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ABSTRACT: The energy levels of 15F have been measured by the p(14O,p)14O reaction. The 120 MeV 14O radioactive ion beam was produced by the BEARS coupled cyclotron system at an intensity averaging 1×104 particles/second on target. Energy calibration was obtained using resonances from the p(14N,p)14N reaction. The two lowest resonances in 15F were fitted with an R-matrix calculation. The fit to the ground state had Jπ=1/2+ at 1.23 ± 0.05 MeV (width 0.5 − 0.84 MeV), and the first excited state was Jπ=5/2+ at 2.81 ± 0.02 MeV (width 0.30 ± 0.06 MeV), both relative to the mass-energy of the proton and 14O. The 15F ground state energy supports the disappearance of the Z = 8 proton magic number for odd Z,Tz=-3/2 nuclei.Phys. Rev. C. 09/2005; 72(3). -
Conference Proceeding: A 16 MeV/nucleon cocktail for heavy ion testing
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ABSTRACT: The operations group at the 88-inch cyclotron at LBNL has developed a new cocktail of heavy ions ranging from Z=7-36 at 16 MeV/nucleon, which provides LETs from 1-26 MeV/mg/cm<sup> 2</sup> at ranges from >500 μm for the lightest components down to 163 μm for krypton. This adds a more penetrating high-LET cocktail to the standard 4.5 MeV/nucleon and 10 MeV/nucleon cocktails presently available. When the new VENUS ion source is coupled to the cyclotron in 2005, xenon will be available as well, at an LET of 48 MeV/mg/cm<sup> 2</sup> and a range of 164 μm.Radiation Effects Data Workshop, 2004 IEEE; 08/2004 -
Article: High-energy heavy ion cocktail beams at the 88 Inch Cyclotron (abstract)
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ABSTRACT: The combination of cyclotron and electron cyclotron resonance (ECR) ion source provides the ability to accelerate “cocktails” of ions, mixtures of ions of near-identical charge-to-mass ratio. This concept was developed soon after the first ECR ion source became operational at the 88 Inch Cyclotron and has become a powerful tool in the field of heavy ion radiation effects testing. The standard 4.5 MeV/nuc cocktail at a charge-to-mass ratio of 0.2 contains ions from B2+ to Bi41+. Copper and cobalt are provided by the direct insertion method, B is produced utilizing the MIVOC technique and Bi is produced with the oven technique. Recently, following upgrades to the AECR and the cyclotron vacuum system, a new high-energy heavy cocktail beam has been developed. This cocktail at a charge-to-mass ration of 0.27 using 400 MeV Ar11+ as a “pilot” beam, contains ions from B3+ to Xe38+ and provides accelerated ions with a range of 100 μm in Si, of great advantage for some of the newer-generation microelectronics. It has joined the 4.5 MeV/u heavy ion cocktail and the 32.5 MeV/u light ion cocktail as standards in the cyclotron’s cocktail repertoire. © 2002 American Institute of Physics.Review of Scientific Instruments 01/2002; 73(2):582-582. · 1.37 Impact Factor -
Article: High energy cocktail beams for radiation effects studies
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ABSTRACT: The 88-Inch Cyclotron facility consists of a sector-focused, variable energy cyclotron fed by two Electron Cyclotron Resonance (ECR) high charge-state sources. The combination of cyclotron and ECR source provides the ability to run ''cocktails'' of ions, mixtures of ions of near-identical charge-to-mass ratio. This concept was developed for detector calibrations soon after the first ECR source came on line. [1] The ions are tuned out of the source together and the cyclotron frequency--acting as a mass analyzer--separates them. This means that within the components of the cocktail, the accelerated ion can be changed in approximately one minute. Intensity variations are compensated for with a series of attenuator grids at the ion source, which allow ion beam intensity adjustments over nine orders of magnitude. The cocktail beam soon became the mainstay of the heavy ion radiation effects program at the Cyclotron, an applied program which is run on a recharge basis and which accounts for about 10% of the annual usage. The largest component of this program is directed at measuring single event effects--a variety of effects, which can occur when a heavy ion traverses a transistor, memory chip or other piece of microelectronics. It can then be determined whether the device is appropriate for use in a satellite or space vehicle in a particular orbit, knowing the distribution of heavy ions expected at that orbit. To first order, the observed single event effects are atomic processes, which depend only on the linear energy transfer (LET), or stopping power, of the ion. The range of the ion is important only to ensure that the ion reaches the correct interaction depth. In the early 90's, two cocktails were developed at the Cyclotron for standard use: a ''light ion'' cocktail for ions up to {sup 36}Ar at high energy and large range, and a ''heavy ion'' cocktail at 4.5 MeV/nucleon, with LETs ranging from 3-60 MeV/mg/cm{sup 2} and ranges from 43-69 {micro}. Using the AECR, Bi could be added, giving a LET of nearly 100 MeV/mg/cm{sup 2}. In recent years, as chip technology advanced and chips became more miniaturized, it has become more difficult to ''delid'' the chips, i.e. remove the layers on top of the active elements to allow the ions to penetrate to the active area. Therefore many users were requesting a higher energy heavy-ion cocktail. With the upgrade of the Advanced ECR source in 1996 and vacuum upgrades to the Cyclotron in subsequent years, it became possible to accelerate a cocktail of beams at 10 MeV/u. This gives LETs not very different than the lower energy cocktail, 0.8-53 MeV/mg/cm{sup 2}, and ranges from 115-330 {micro}. The ''standard'' components of this cocktail are given in Table 1. Other beams (Mg, Ge, Mo) can be found at lower intensities. This cocktail now accounts for approximately 50% of the radiation effect work done at the 88-Inch Cyclotron.12/2000; -
Article: Measurement of Excitation Functions in the Reactions {sup 197}Au( {sup 11}C, xn){sup 208-x}At Using a Radioactive {sup 11}C Beam
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ABSTRACT: A light-element radioactive ion-beam capability has been developed at the LBNL 88-Inch Cyclotron. The system is based on the coupled-cyclotrons method and utilizes short-lived species, e.g., {sup 11}C , {sup 14}O , {sup 13}N produced by (p, n) and (p, {alpha}) reactions at the LBNL Biomedical Isotope Facility Cyclotron. In a first experiment, {sup 197}Au({sup 11}C, xn){sup 208-} {sup x}At excitation functions have been measured for energies ranging from the Coulomb barrier up to 110 MeV using a beam of {sup 11}C with intensities up to (1-2)x10{sup 8} ions/sec on target. The results of this experiment are compared to measurements of {sup 197}Au({sup 12}C, xn){sup 209-} {sup x}At excitation functions. (c) 2000 The American Physical Society.Physical Review Letters 05/2000; 84(22). · 7.37 Impact Factor -
Conference Proceeding: Radiation effects testing at the 88-inch cyclotron
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ABSTRACT: The 88-inch cyclotron at the Lawrence Berkeley National Laboratory provides radiation effects test facilities for both heavy ions and protons. The wide range of ions available, and the use of “cocktail” beams, allowing users to switch back and forth between several heavy ion beams without a retune of the accelerator, makes this facility a very versatile and economical choice for radiation effects testingRadiation and Its Effects on Components and Systems, 1999. RADECS 99. 1999 Fifth European Conference on; 02/1999 -
Conference Proceeding: BEARS (Berkeley Experiments with Accelerated Radioactive Species)
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ABSTRACT: The BEARS project at Lawrence Berkeley National Laboratory is developing the capability for some proton-rich radioactive beams using a coupled-cyclotron method. Initial studies have focused on <sup>11</sup>C and <sup>14</sup>O and the first physics experiment is complete using <sup>11</sup>C in batch mode. Ionization efficiencies have been measured as high as 11% for <sup>11</sup>C<sup>+4</sup>. The total efficiency for ionization and acceleration is approximately 1% and total beam intensities of 1×10<sup>8</sup> have been observed. Upon completion of the transfer line, beam intensities of 2×10<sup>8 </sup> are expected for <sup>11</sup>C and 5×10<sup>6</sup> for <sup>14</sup>OParticle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999 -
Article: Neutron yields from 435 MeV/nucleon Nb stopping in Nb and 272 MeV/nucleon Nb stopping in Nb and Al.
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ABSTRACT: Neutron fluences were measured from 435 MeV/nucleon Nb ions stopping in a Nb target and 272 MeV/nucleon Nb ions stopping in targets of Nb and Al for neutrons above 20 MeV and at laboratory angles between 3 degrees and 80 degrees. The resultant spectra were integrated over angles to produce neutron energy distributions and over energy to produce neutron angular distributions. The total neutron yields for each system were obtained by integrating over the angular distributions. The angular distributions from all three systems are peaked forward, and the energy distributions from all three systems show an appreciable yield of neutrons with velocities greater than the beam velocity. Comparison of the total neutron yields from the two Nb + Nb systems suggests that the average neutron multiplicity decreases with decreasing projectile energy. Comparison of the total yields from the two 272 MeV/nucleon systems suggests that the total yields show the same dependence on projectile and target mass number as do total inclusive neutron cross sections. The data are compared with Boltzmann-Uehling-Uhlenbeck model calculations.Physical Review C 01/1999; 58(6):3451-61. · 3.31 Impact Factor -
Article: Neutrons from multiplicity-selected La-La and Nb-Nb collisions at 400A MeV and La-La collisions at 250A MeV
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ABSTRACT: Triple-differential cross sections for neutrons from high-multiplicity La-La collisions at 250 and 400 MeV per nucleon and Nb-Nb collisions at 400 MeV per nucleon were measured at several polar angles as a function of the azimuthal angle with respect to the reaction plane of the collision. The reaction plane was determined by a transverse-velocity method with the capability of identifying charged-particles with Z=1, Z=2, and Z > 2. The flow of neutrons was extracted from the slope at mid-rapidity of the curve of the average in-plane momentum vs the center-of-mass rapidity. The squeeze-out of the participant neutrons was observed in a direction normal to the reaction plane in the normalized momentum coordinates in the center-of-mass system. Experimental results of the neutron squeeze-out were compared with BUU calculations. The polar-angle dependence of the maximum azimuthal anisotropy ratio $r(\theta)$ was found to be insensitive to the mass of the colliding nuclei and the beam energy. Comparison of the observed polar-angle dependence of the maximum azimuthal anisotropy ratio $r(\theta)$ with BUU calculations for free neutrons revealed that $r(\theta)$ is insensitive also to the incompressibility modulus in the nuclear equation of state.12/1998; -
Conference Proceeding: Cocktails and other librations-the 88-inch cyclotron radiation effects facility
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ABSTRACT: The 88-inch cyclotron at the E.O. Lawrence Berkeley National Laboratory has unique capabilities of advantage for radiation effects testing (RET) and detector calibrations for space applications. The ability to deliver from protons (low linear energy transfer (LET) and high range) to bismuth (LET=100 MeV/mg/cm<sup>2</sup>), and most ions in between, makes the cyclotron facility a versatile cosmic ray factory on Earth. In addition, the availability of “cocktail” beams of several ion species allows the luxury of testing parts over a range of LET values with one tuneup, saving time and moneyRadiation Effects Data Workshop, 1998. IEEE; 08/1998 -
Conference Proceeding: Beams for Gammasphere at the LBNL 88-inch cyclotron
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ABSTRACT: The new transport system from the 88-inch cyclotron to the Gammasphere facility is described. Included are discussions of the ECR sources, operation, beam diagnostics, mechanical construction, vacuum system and beam opticsParticle Accelerator Conference, 1997. Proceedings of the 1997; 06/1997 -
Article: The response of scintillators to heavy ions-I. Plastics
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ABSTRACT: The response of various scintillator detectors to ions of A=1-84 and energies E/A=5-30 MeV has been measured and found to be linear above an energy of 100 MeV. Results are presented for a typical organic plastic scintillator including parameterizations of the data as a function of Z, A, and energy. These results are applicable to the use of scintillators as heavy-ion detectors, with one calibration point giving a normalization that allows use of the whole set of curves. The response functions are compared to previous parametrizations at lower energies and discussed in terms of the theory of delta -ray formation in the scintillator.IEEE Transactions on Nuclear Science 03/1988; · 1.45 Impact Factor -
Article: Neutron beams from deuteron breakup at the 88-Inch cyclotron at Lawrence Berkeley National Laboratory
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ABSTRACT: Accelerator-based neutron sources offer many advantages, in particular tunability of the neutron beam in energy and width to match the needs of the application. Using a recently constructed neutron beam line at the 88-Inch Cyclotron at LBNL, tunable high-intensity sources of quasi-monoenergetic and broad spectrum neutrons from deuteron breakup are under development for a variety of applications. -
Article: Neutrons from multiplicity-selected La-La and Nb-Nb collisions at 400A MeV and La-La collisions at 250A MeV
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ABSTRACT: Triple-differential cross sections for neutrons from high-multiplicity La-La collisions at 250 and 400 MeV per nucleon and Nb-Nb collisions at 400 MeV per nucleon were measured at several polar angles as a function of the azimuthal angle with respect to the reaction plane of the collision. The reaction plane was determined by a transverse-velocity method with the capability of identifying charged-particles with Z=1, Z=2, and Z>2. The flow of neutrons was extracted from the slope at mid-rapidity of the curve of the average in-plane momentum vs the center-of-mass rapidity. The squeeze-out of the participant neutrons was observed in a direction normal to the reaction plane in the normalized momentum coordinates in the center-of-mass system. Experimental results of the neutron squeeze-out were compared with BUU calculations. The polar-angle dependence of the maximum azimuthal anisotropy ratio r(θ) was found to be insensitive to the mass of the colliding nuclei and the beam energy. Comparison of the observed polar-angle dependence of the maximum azimuthal anisotropy ratio r(θ) with BUU calculations for free neutrons revealed that r(θ) is insensitive also to the incompressibility modulus in the nuclear equation of state.Phys. Rev. C. 59(1). -
Article: Production of neutrons from interactions of GCR-ldce particles
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ABSTRACT: In order to help assess the risk to astronauts due to the long-term exposure to the natural radiation environment in space, an understanding of how the primary radiation field is changed when passing through shielding and tissue materials must be obtained. One important aspect of the change in the primary radiation field after passing through shielding materials is the production of secondary particles from the breakup of the primary. Neutrons are an important component of the secondary particle field due to their relatively high biological weighting factors, and due to their relative abundance, especially behind thick shielding scenarios. Because of the complexity of the problem, the estimation of the risk from exposure to the secondary neutron field must be handled using calculational techniques. However, those calculations will need an extensive set of neutron cross section and thick-target neutron yield data in order to make an accurate assessment of the risk. In this paper we briefly survey the existing neutron-production data sets that are applicable to the space radiation transport problem, and we point out how neutron production from protons is different than neutron production from heavy ions. We also make comparisons of one the heavy-ion data sets with Boltzmann-Uehling-Uhlenbeck (BUU) calculations.Acta Astronautica. -
Article: Production of a $^76$Kr radioactive ion beam using a batch mode method
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ABSTRACT: A batch mode process has been developed to produce a 76Kr (T1/2 = 14.8 h) radioactive ion beam at the Lawrence Berkeley National Laboratory 88-in. Cyclotron. First, a 6 particle ?A ? beam is run for 17 h to produce approximately 101476Kr atoms via the reaction 74Se(?, 2n)76Kr. Then, the krypton is separated from the target material and injected into the AECR-U ion source. Beam intensities as high as 3 × 108 particles per second are observed with an integrated beam current of 6(2) × 1011 particles per 24-h batch cycle. © 2004 Published by Elsevier B.V.NIM A. 533(3):287-294. -
Article: First g-factor measurement using a radioactive $^76$Kr beam
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ABSTRACT: The g factor of the first 2+1 state of radioactive 76Kr ( T 1/2 = 14.8 h) has been measured using projectile Coulomb excitation in inverse kinematics combined with the transient magnetic-field technique. The 76Kr beam was produced and accelerated in batch mode (re-cyclotron method) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The g factor g(76Kr; 2+1) = +0.37(11) was obtained. © Societa? Italiana di Fisica / Springer-Verlag 2005.Eur. Phys. J. A. 25(SUPPL. 1):203-304. -
Conference Proceeding: First Measurement of a Magnetic Moment of a Short-Lived State with an Accelerated Radioactive Beam: $^76$Kr
"Key Topics in Nuclear Structure", Proceedings of the 8th International Spring Seminar on Nuclear Physics, Paestum, Italy, May 23-27;
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1988–2005
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Lawrence Berkeley National Laboratory
- Nuclear Science Division
Berkeley, CA, USA
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