D. J. Clark's research while affiliated with University of California, Berkeley and other places
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Publications (32)
A cryogenic vacuum pumping panel has been in operation at the 88-inch cyclotron since 1974. The nude pumping panel is located in the acceleration chamber. The pumping surface consists of tubing cooled to 20°K by a closed loop helium refrigeration system. The pumping surfaces are shielded from radiation heat loads and water vapor by liquid nitrogen...
Recent advances in design and operation of the internal PIG sources at the LBL 88-Inch Cyclotron have led to the development of high charge state (0.4 ¿ Q/A ¿ 0.5) heavy ion beams between lithium and neon with energies 20 ¿ E/ A ¿ 32 MeV ger nucleon, including fully stripped ions up to l6o8+. Total external intensities of these beams range from...
A two year design study has been completed for medical ion accelerators with beams of sufficient range and intensity for therapy. The particles of main interest were ions between carbon and neon, but the generation of proton and neutron beams was studied also. Cyclotrons appear to be good injectors for a heavy ion medical synchrotron, particularly...
A modern isochronous cyclotron requires a large number of control settings to produce a wide variety of beams and energies. During fifteen years of operating experience with the Berkeley 88” cyclotron we have developed a system for prediction of parameters for new beams. This system substantially reduces the accelerator time required for their impl...
A method is discussed for using the Berkeley 88″ cyclotron as a mass spectrometer for all atomic masses. Low background radiation permits the detection of trace elements with a sensitivity of 1 part in 105–1017, a mass accuracy of Δm/m = 5.8 × 10−5, and an abundance accuracy of a few percent. These results are based in part on mass scans using an i...
The emittances of beams of Ar4+ to Ar8+ have been measured in the axial and radial planes. The extraction voltage was 10 kV and the magnetic field was varied from about .5 to .6 Tesla. The anode slit was varied in its distance from the arc which was run both dc and pulsed. The emittance was found to be nearly independent of charge state but to incr...
The comparison of pulsed vs. dc arc operation for nitrogen and argon shows a shift in charge distribution toward the higher charge states for the pulsed case. Tests with various magnetic field shapes along the arc column show a significant increase in high charge state output for a uniform field compared to the case with a field low at the cathodes...
A brief design study has been done for a 150 MeV proton sector cyclotron. The object was to minimize cost but maintain good reliability and easy maintenance. The use of the proton beam would be for therapy, radiography and isotope production.
Design studies on four booster cyclotrons for heavy ions are described. Comparisons are made of normal vs. super conducting main coils, and K = 400 and 800 sizes. Performance and cost estimates are given.
Not Available Address: Lawrence Berkeley Lab. Berkeley, Ca.
A new internal heavy ion source of the Penning type has “been in operation at the Berkeley 88‐Inch Cyclotron for 10 months. Beams of lithium,
carbon, nitrogen, oxygen, neon, and iron have been accelerated and used in experiments in the energy range 4–l8 MeV/nucleon. External beam intensities are 1–10 μA of most carbon, nitrogen, and oxygen beams....
A new internal Penning ion source is now being tested for production of nitrogen and oxygen beams. Nitrogen beams of N5+ have been accelerated to 250 MeV. An external source for lithium beams is being developed.
Electron cyclotron resonance was detected in a Penning source by measuring the electron temperature as obtained from the x-ray emission spectrum. The resonance is only present if flat cathodes are used.
Proceedings contain the texts of 54 papers presented at the conference and summaries of the discussions that followed many of the presentations. Work on gaseous discharge sources, operating Penning sources, new source concepts, accelerator topics, negative ion sources and charge exchange phenomena, and new concepts of accelerator systems for heavy...
A heavy ion source of the PIG type has been installed on the axial injection line at the 88-Inch Cyclotron. It is now in the testing phase. Arc powers up to 4 kW have been run, and hydrogen and nitrogen beams have been injected and accelerated in the cyclotron.
The slit scattering effect has been measured for medium energy protons and alpha particles on aluminum, brass and tantalum slits. A successful comparison with the theoretical treatment of Courant has enabled us to predict the slit scattering effect for our experimental conditions lending credence to the application of the Courant theory to other ex...
A new axial injection system for the 88-inch cyclotron has been constructed. It transports beams from external ion sources axially through the magnet yoke to the median plane of the cyclotron. The optical elements include a bending magnet, electric quadrupoles, and the magnetic field of the cyclotron. Beam monitoring is done with scanning wires. ph...
Machine development at the 88-inch cyclotron is described. Topics include instrumentation, deflector development, a radioactivity survey of the dee tank, and computer calculations on the gap-crossing resonance. Studies were made of external beam energy spread and pulse shape. Axial injection progress is described. Recommendations are made for desig...
Methods of cyclotron beam development and diagnostics are described. Techniques for measuring the space, time and energy distributions of both internal and external beams are included. Emphasis is on the more recent methods commonly used at many laboratories.
The electro-static regenerative beam extraction system for the Berkeley 88" cyclotron is described. Results of the orbit studies using the modified general orbit code are shown. The design features of the regenerator with a 3 section electro-static deflector are given. The results obtained from the machine tests are summarized.
Studies are in progress on possible improvements of the center region and extraction system of the 184-in. cyclotron. The center region is being studied with a 28-in. model proton cyclotron, which has been operated without frequency modulation at 16 and 23 kG and at 1% duty cycle. Frequency modulation has now been added to study space charge and ca...
The goal of the program of ion source development for an rf linac has been to produce currents of up to 100 mA of the heavier gaseous ions such as argon and xenon, of good emittance (.02 ..pi.. cm mr, normalized) and charge state 1/sup +/. Existing facilities and hardware utilized included the 470 kV Bevatron injector, the 750 kV injector for the 5...
Synchrotrons and cyclotrons have an overlap in their particle and energy ranges. In proton radiotherapy, synchrotrons are proposed at 250 MeV, an energy usually served by cyclotrons. Heavy ion therapy has been synchrotron territory, but cyclotrons may be competitive. In nuclear science, heavy ion synchrotrons can be used in the cyclotron energy ran...
Citations
... It has been observed for the facility at TRIUMF to be on the order of a few percent. [9] Slit scattering has been well studied for many years both theoretically and experimentally [10,11] and can be minimized by careful design of the collimators or slits. ...
... The lithium ion beams are widely used in neutral lithium beam injectors for beam emission spectroscopy measurements on fusion experiments [1], neutralization on the metal surface [2], p( 7 Li,n) 7 Be neutron source [3], et al. . Normally, the lithium beams can be generated by electron cyclotron resonance ion sources (ECRIS) [4], surface ionization sources [5], laser beam ion sources [6], PIG sources [7]. ...
... The Dee probe [2,3] is mounted at the end of a shaft that moves radially inward. The probe is unsuppressed, but it is partially magnetically shielded by the main magnet field. ...
Reference: Trim Coil Unbalance of the 88-Inch Cyclotron
... With the conventional diagnostic methodologies [4] such as slit-scanning and quadrupole scanning [5], commissioning of Garam a LEBT line with the required beam quality is time consumingand costly. In addition, these methods are not suitable for measuring horizontal-vertical coupling terms. ...
