Ionacoustic in-person gathering at Imperial: 24Jul23

Present: JB, BC, MM, KL

Meeting was arranged to try to identify the acoustic sensor to be used in the proof-of-principle experiment. Discussion extended beyond this. These notes are conclusions or actions only.

Goal of proof-of-principle experiment:
Raised by BC, we agreed it would be valuable to identify our aims for the PoP experiment. In our discussion we propose:

• Principal aims:
  • Demonstration that dose profile can be reconstructed;
  • Demonstration that acoustic signal can be calibrated into energy (dose) deposited.
• Secondary aims:
  • Demonstrate we can record the signals and interpret the results.

Sensor choice:
We did not finalise the acoustic sensor specification. However, we agreed:

• Plan on assumption that we can negotiate a loan of a sensor array from ICR.
• Ideally would use 2D sensor array (32 x 32 sensors). Alternatively, use a linear array. We discussed pros and cons, coupling to water phantom, etc.
• Maintain the option of simultaneously using single element transducers in locations not occupied by the sensor array. This would be in the longitudinal direction and also the side views.
• Required range of frequencies, sensitivity and SNR critical to understand. So, agreed on need to study frequency spectrum generated by a variety of beam shapes and energies. These would then be used to finalise specification for the beam so that it would generate acoustic signals matched to the response of the transducers.

Going forward:
We agreed it would be important to initiate a rolling programme of such in-person meetings. Agreed to propose monthly in-person meetings to the group. Plan to start at the beginning of September.

Actions:

• MM: Use "ideal beam" with defined central energy and energy spread to study acoustic signals. Study would include using manufacturers performance characteristics for the transducers, various beam energies, energy spreads, size, sampling direction, pulse duration, repetition rate, ...
• KL/MM/RR: Pursue linear optics simulation to try and reduce execution time to allow optimisation studies.
• MM/BC/All: Work on table to distill literature review, recording the energy, energy spread, size, pulse duration, rep. rate, sensor position, number of channels, pre-amp characteristics, Make/model of transducer, central frequency and bandwidth, ... and a measure of the experiments success.
• MM: Doodle for in person meetings now to Christmas.
• All: Seek response to in-person meeting concept at Thursday's ion acoustic meeting and finalise the date(s).

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