Showing papers by "D.L. Friesel published in 1995"

Effects of RF voltage modulation on particle motion

Abstract: The effects of rf voltage modulation on synchrotron motion were studied experimentally. The experimental data revealed the resonance islands generated by the rf voltage modulation. With electron cooling, beam particles were observed to damp to the basins of these resonance islands or attractors, which were observed to rotate about the origin of the phase space at a half of the modulation frequency. The measured amplitude of the attractors as a function of the modulation frequency agreed very well with the theoretical prediction. The Poincare maps in the resonance rotating frame were obtained from the experimental data and compared with tori of the Hamiltonian flow. Based on our theoretical formulation, slow beam extraction using rf voltage modulation and a bent crystal are also studied.

Temperature sensitivity of surface channel effects on high-purity germanium detectors

Abstract: The temperature sensitivity of surface channel effects on planar high-purity germanium detectors was measured using 60-keV gamma-ray scanning techniques, as part of a radiation damage study. When measured in this manner, the surface effects on most detectors showed extreme temperature sensitivity in the 72–95 K region. The effect of the surface channel increased with increasing temperature to such an extent that the efficiency, as measured by the count rate in the 1332-keV peak from a 60Co source, decreased by a factor of over two in some cases. Since the peak efficiency for the 1332-keV gamma ray decreased as the temperature increased throughout the operating range (72–120 K) the effect of the surface channel must continue to increase beyond the temperature (95 K) at which the 60-keV scan loses its sensitivity because of the strong attenuation of these much lower energy gamma rays. Radiation damage had no measurable effect on the surface characteristics. No correlation between the surface effects and the resolution changes of the 1332-keV peak was observed.

The Indiana University Cooler injection synchrotron RF cavity

Abstract: A small 2.2 Tesla-meter booster synchrotron is under construction at the Indiana University Cyclotron Facility to boost polarized beam performance in the electron cooled Indiana University Cooler Synchrotron. Polarized light proton or deuteron beam from a high intensity polarized ion source will be preaccelerated to 7 and 6 MeV respectively by an RFQ/DTL accelerator. The beams are then debunched to reduce the energy spread and strip-injected into the booster synchrotron. The booster RF system must accomplish the tasks of beam capture and acceleration. At the end of the acceleration cycle, the beam phase needs to be aligned to the Cooler synchrotron RF for bucket-to-bucket beam transfer. A single RF cavity in the ring will provide the necessary RF field to accomplish the above tasks.

The Indiana University Cooler injector synchrotron RF system

Abstract: A 2.2 Tesla-meter synchrotron with 17.4 m circumference is being built at the Indiana University Cyclotron Facility (IUCF). The purpose of the project is to achieve higher luminosity for nuclear physics experiments using electron cooled polarized light ion beams in the IUCF Cooler synchrotron. The injection line for the booster synchrotron consists of an RFQ/DTL linear accelerator delivering a 7 MeV proton beam and a 6 MeV deuteron beam for the booster injection. A debunching system will be installed in the injection beamline to reduce the energy spread of beams out of the linear accelerators. Charge-exchange injection is used for high intensity multiturn beam accumulation. The booster output beams, 200 MeV for protons and 105 MeV for deuterons, will be transferred bucket to bucket to the IUCF Cooler synchrotron. The rf system design for the booster synchrotron is presented in this paper.

CIS, a low energy injector for the IUCF cooler

Abstract: Construction has begun on a low energy booster synchrotron to replace the IUCF isochronous cyclotrons for the injection of polarized light ions into the existing 3.6 T-m electron-cooled storage ring (cooler). CIS (cooler injector synchrotron), with a circumference of 1/5th the cooler ring, will provide /spl ges/2.5/spl middot/10/sup 10/ polarized protons (deuterons) per pulse at 1 Hz for cooler injection. Bucket-to-bucket beam transfer from CIS to the cooler operating on the 5th harmonic will fill the cooler with 10/sup 11/ protons in 5 sec. The higher intensity and improved duty cycle will enhance the range and quality of experimental nuclear physics research programs using cooler beams.

Parametric resonances and stochastic layer induced by a phase modulation

Abstract: The Hamiltonian system with phase modulation in a higher harmonic RF cavity is experimentally studied on the IUCF cooler ring. The Poincare maps in the resonant rotating frame are obtained from experimental data and compared with numerical tracking. The formation of the stochastic layer due to the overlap of parametric resonances is discussed. The dependence of the stochastic layer on the voltage of the higher harmonic RF cavity, amplitude and frequency of the phase modulation is studied.

The lattice design of Indiana University Cyclotron Facility Cooler Injector Synchrotron

Abstract: This paper reports lattice design studies of a low energy booster at the Indiana University Cyclotron Facility (IUCF). This booster will be used as an injector, which is named as Cooler Injector Synchrotron (CIS), for the existing IUCF Cooler ring. The IUCF CIS will be able to accelerate high-intensity polarized protons or deuterons coming from a RFQ linac from 7 MeV (6 MeV) to 200 MeV (105 MeV). The beam bunch then will be extracted and injected into the Cooler ring for further acceleration. The finalized lattice design for the CIS has four superperiods. Each period is composed of a drift space and a dipole magnet which has 90/spl deg/ bending angle and 12/spl deg/ edge angle at both ends. The circumference of the CIS is 17.364 meters, one fifth of that of the Cooler ring. The designed horizontal and vertical tunes are 1.463 and 0.779, respectively. Possible effects from the employment of trim quadrupoles, which will be located between dipoles, are also discussed.