A custom waveguide dc break, developed for the versatile ECR for nuclear science (VENUS) ion source at Lawrence Berkeley National Laboratory, features an innovative impedance matching network. This network consists of two inductive irises located adjacent to a capacitive gap, which not only provides dc isolation but also facilitates the coupling of a new 2.4 kW Klystron, effectively doubling the power available for plasma production at the secondary frequency of 18 GHz. The design allows the ion source to operate at elevated potentials while keeping the RF system grounded, thereby ensuring efficient ion beam extraction and transportation to the cyclotron for acceleration, and maintaining easy access to the RF system. Simulations conducted with the ANSYS High-Frequency Structure Simulator, a finite element analysis tool, have demonstrated exceptional impedance matching at the Klystron frequency. These results have been corroborated by microwave measurements, showing excellent agreement.

The potential of particle therapy due to focused dose deposition in the Bragg peak has not yet been fully realized due to inaccuracies in range verification. The purpose of this work was to correlate the Bragg peak location with target structure, by overlaying the location of the Bragg peak onto a standard ultrasound image. Pulsed delivery of 50 MeV protons was accomplished by a fast chopper installed between the ion source and the cyclotron inflector. The chopper limited the train of bunches so that 2 Gy were delivered in 2 μs. The ion pulse generated thermoacoustic pulses that were detected by a cardiac ultrasound array, which also produced a grayscale ultrasound image. A filtered backprojection algorithm focused the received signal to the Bragg peak location with perfect co-registration to the ultrasound images. Data was collected in a room temperature water bath and gelatin phantom with a cavity designed to mimic the intestine, in which gas pockets can displace the Bragg peak. Phantom experiments performed with the cavity both empty and filled with olive oil confirmed that displacement of the Bragg peak due to anatomical change could be detected. Thermoacoustic range measurements in the waterbath agreed with Monte Carlo simulation within 1.2 mm. In the phantom, thermoacoustic range estimates and first-order range estimates from CT images agreed to within 1.5 mm.

The 4.5 MeV/nucleon heavy ion cocktail at the 88-Inch Cyclotron has been expanded by incorporating beams from solid material to fill in the linear energy transfer curve. This supercocktail is available by special request and is useful when only normal incidence between the beam and the device under test is possible or desirable.

The BASE Light Ion Facility upgrades have been completed. All proton beams are now delivered to Cave 4A. New control software, a larger diameter beam window, and improved quality assurance measures have been added.