Abstracts Brochure - CERN

TUOCFI01
TUOCFI02
TUOCFI03
27-Jun-06 14:00 - 15:00 TUOCFI — Accelerator Technology
TUOCFI — Accelerator Technology
Radiation Measurements vs. Predictions for SNS Linac Commissioning
Detailed predictions for radiation fields, in-
I.I. Popova, F. X. Gallmeier, P. L. Gonzalez, D. C. Gregory (ORNL) duced inside and outside of the accelerator
tunnel, were performed for each of the SNS
accelerator commissioning stages, from the ion source through the entire LINAC. Analyses were performed for normal
commissioning parameters, for worst possible beam accidents, and for beam fault studies, using the Monte Carlo
code MCNPX. Proper temporary shielding was developed and installed in local areas near beam termination points
(beam stops) and some critical locations, such as penetrations, in order to minimize dose rates in general occupied
areas. Areas that are not full-time occupied and have dose rates above a specified limit during beam accident and
fault studies were properly restricted. Radiation monitoring was performed using real time radiation measurement
devices and TLDs to measure absorbed dose and dose equivalent rates. The measured radiation fields were analyzed
and compared with transport simulations. TLD readings vs. calculations are in a good agreement, generally within
a factor of two difference. A large inconsistency among instrument readings is observed, and an effort is underway
to understand the variations.
First Results of SNS Laser Stripping Experiment
V.V. Danilov, A.V. Aleksandrov, S. Assadi, J. Barhen, Y. Braiman,
D.L. Brown, W. Grice, S. Henderson, J.A. Holmes, Y. Liu, A.P.
Shishlo (ORNL)
Thin carbon foils are used as strippers for
charge exchange injection into high intensity
proton rings. However, the stripping foils become
radioactive and produce uncontrolled
beam loss, which is one of the main factors
limiting beam power in high intensity proton rings. Recently, we presented a scheme for laser stripping of an H −
beam for the SNS ring. First, H − atoms are converted to H0 by a magnetic field, then H0 atoms are excited from
the ground state to the upper levels by a laser, and the excited states are converted to protons by a magnetic field.
This paper presents first results of the SNS laser stripping proof-of-principle experiment. The experimental setup is
described, and possible explanations of the data are discussed.
RF Cavity with Co-based Amorphous Core
A compact acceleration cavity has been
M. Kanazawa, T. Misu, A. Sugiura (NIRS)
developed with new Co-based amorphous
cores, which will be used in a dedicated synchrotron
for cancer therapy. This core has high permeability that makes the cavity length short, and the cavity with no
tuning system is possible with low Q-value of about 0.5. An acceleration cavity consists of two units that have a single
acceleration gap at the center, and at the both side of the gap there are quarter wave coaxial resonators. Considering
the requirements for easy operation, a transistor power supply was used instead of commonly used tetrode in the
final stage RF amplifier. Each resonator has maximum impedance about 400? at 3MHz, and has been attached with
1:9 impedance transformer. In the frequency range from 0.4 to 8 MHz, the acceleration voltage of more than 4kV can
be obtained with total input RF power of 8kW. With these performances, the cavity length is short as 1.5m. In this
paper the structure of the cavity and their tested high power performances are presented.
158 Chair: A. Mosnier (CEA, Gif-sur-Yvette)