A. Zucker

Energy dependence of the elastic scattering and polarization of protons on 40Ca

Abstract Absolute differential cross sections and polarizations for elastic proton scattering from 40 Ca were measured at incident proton energies of 35.8 and 45.5 MeV. These data, together with similar data at 30.0 and 40.0 MeV, were analysed with a fixed geometry optical potential to obtain an energy dependence of the real-central well for 40 Ca of d V 0 /d E = −0.32. Unsatisfactory optical-model fits to the large angle data are shown to be easily improved by a slight adjustment of the reflection coefficients associated with the nuclear associated with the nuclear surface. Calculated phase shifts give no indication of elastic scattering resonances in the energy range 30.0 ≦ E p ≦ 45.5 MeV.

Polarized-proton scattering facility at the Oak Ridge isochronous cyclotron☆

Abstract In the facility described, polarized-proton beams are produced either as recoil protons from a hydrogen-gas target bombarded by α-particles or as elastically scattered protons from a solid 40 Ca target. At a polarized-proton energy of 40 MeV, the polarization is 89±7% for the hydrogen polarizer and 35.5±3% for the 40 Ca polarizer. A system of two quadrupole-doublet lenses transports the polarized proton beam about 18 ft and focuses the beam to a 1 4 ″ by 1″ spot at the center of a scattering chamber. Energy spectra of protons scattered from a secondary target are obtained at 32 angles simultaneously by using 32 NaI scintillation counters connected to the X-ADC of a Victoreen 20 000-channel multiparameter analyzer used as thirty-two 400-channel analyzers.

Concepts of an Mc2 cyclotron

A source of high energy protons and π and μ mesons of unprecedented intensity should result from a large isochronous cyclotron now under study. An intense beam of protons at approximately 800 MeV can be deflected from this eight-sector machine at the 8/4 resonance. Model studies have also shown that internal beams with energies above Mc 2 are possible. The maximum orbit radius is 6 m (20 ft); the outer radius of the machine is 9 m. From the design of a 0.15 scale model, with three of the eight sectors, it is estimated that the full scale magnet would require about 5000 tons of steel and 10 MW of magnet power. R.f. excitation by resonant cavity is planned, with several possible configurations under study. Shielding of experimental areas of adequate size will require use of earth or compacted aggregate to achieve reasonable economy. Studies of induced activity suggest that the use of aluminium, iron, and carbon in strategic areas and the elimination of nickel and perhaps a few other materials, will make management of activity levels feasible.

Radiation survey at the LRL 184-inch cyclotron

To predict the radioactivity problems to be anticipated with a high-intensity, Mc 2 accelerator, the residual and induced radioactivities were measured at the 184-Inch Berkeley cyclotron during November 1960. The five-day study included a general survey of radiation levels in the cyclotron vault, short-time activation of foils placed near the cyclotron, and analysis of γ-ray spectra of the cyclotron gap region, including dee structure. Initial radiation levels were less than 8 r/hr; these dropped to about 10 mr/hr after 48 hr. The induced activities in foils were: Cu 64 and Co 58 in copper, Mn 32 , Mn 54 , and Mn 56 in iron; and Na 24 in aluminum. The γ-ray spectra from the gap region show two intense long-lived peaks at 510 and 810 keV, probably from Co 53 . Foils of aluminum, brass, copper, nickel, and steel were then attached to one of the pole pieces and left i n the cyclotron for one year. The γ-ray spectra of these foils were later analyzed for the presence of induced long-lived activities. The foils can be grouped in order of increasing amount of induced activity at saturation bombardment as follows: aluminum, copper, brass, steel, and nickel. The preliminary conclusion is that with proper precautions a 100-μA Mc 2 cyclotron could have a long-lived background less than 1 r/hr.