Accelerators (<1 MeV/n) for Low-Energy Measurements Workshop on Underground Accelerators for Nuclear Astrophysics October 27-28, 2003 Jose Alonso, Rick Gough Lawrence Berkeley National Laboratory. Outline.
Workshop on Underground Accelerators for
October 27-28, 2003
Jose Alonso, Rick Gough
Lawrence Berkeley National Laboratory
• Higher beam energies
• Ion source at ground
• Requires negative
ion source which limits
current and ion species
• Strip to q+ in
high voltage dome
• E/A = V (q+1)/A
Pelletron (1 - 5 MV)
National Electrostatics Corporation
Open air systems for
lower beam energies
(1 - 500 keV)
Pelletron charging principle
TUNL, ca 1980??
• Open air electrostatic systems used as traditional linac injectors
– require lots of space, largely being replaced by RFQs
• RFQs are compact and efficient
– tunability and low DE/E problematic
for this application
500 kV open-air injector at Livermore
2.5 MeV H– RFQ
built by LBNL for SNS
• Dynamitron from Boeing Radiation
Effects Lab shown w/cover removed
• Require high pressure gas ( SF6 )
• Dynamitron was used as HILAC
injector and is in use at Argonne for radioactive beam studies
2 MV pulsed ESQ accelerator
for fusion energy (base program)
2.5 MV CW ESQ accelerator
for BNCT (spin-off application)
25 mA protons
coaxial transformer power supply
Electric field lens
Magnetic field lens (best at high beam energy)
ESQ module for 4 parallel beams
LUNA Collaboration, INFN, Gran Sasso
Requirement: 50 eµA up to 0.5 MeV/nucleon protons to argon
E / A = 9 / 40 x 2.5 = 0.56 MeV / amu
ECR Ion Source in HV terminal
Tokai Research Establishment, Japan
Ar8+ 2eµA at 112 MeV
• Maximum beam energies?(rest-frame, to determine accel. potential)
• Range of energies needed?(tunability, energy precision)
• Short / long term energy stability(high voltage control, ripple)
• Energy spread?(ion source temperature or RF accelerator design)
• Ion species needed?
• Purity of ion species?
– heavy ions with q/A = 0.5 likely to have contaminants
– molecular, charge-state ambiguities
• What beam currents are required?
• What are the beam current stability requirements?
• Beam-on-target requirements?(spot size…)
• Duty factor(CW or pulsed? Is RF structure OK?)
• Noise constraints?
– could x-rays beyond some energy interfere w/ exp. signals?
– are accelerator-produced neutrons a background problem?
• Site constraints?
– space, access, power, utilities, special safety issues...
• Configuration flexibility?
– may be necessary to have more than one accelerator system to
meet all requirements