Changes between Version 1 and Version 2 of Research/Instrumentation/IonAcoustic/Meetings/2021/10/06


Ignore:
Timestamp:
Oct 6, 2021, 8:57:13 AM (3 years ago)
Author:
longkr
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • Research/Instrumentation/IonAcoustic/Meetings/2021/10/06

    v1 v2  
    1 = LhARA ionacoustic dose profiling meeting: 29Sep21; 09:00 BST =
     1= LhARA ionacoustic dose profiling meeting: 06Oct21; 09:00 BST =
    22
    3 == Notes ==
     3== Agenda ==
    44
     51. //Introduction, [wiki:Research/Instrumentation/IonAcoustic/Meetings/2021/09/29 notes and actions of previous meeting]//: **KL/All**
     6 * **KL** – continue simulations, how to visualise HT’s results and see where to put the transducers
     7  - **Ongoing/stands:** Issue of visualisation not resolved; too many interrupts related to teaching and start of term.
     8 * **BC and EH** - work on specifying the acoustic detectors
     9  -
     10 * **EH** – send info. on passive cavitation detectors, get quotes for acoustic kit
     11  -
    512
    6 {{{
     132. //Discussion: proposal planning and next steps//: **All**
     14
     153. //AOB//: **All**
     16
     17----
     18
     19{{{#!comment
    720#!html
    821<p style="text-align: right">
     
    1124}}}
    1225
    13 == Agenda ==
    14 
    15 === Actions: ===
    16 * **KL** – continue simulations, how to visualise HT’s results and see where to put the transducers
    17 * **BC and EH** - work on specifying the acoustic detectors
    18 * **EH** – send info. on passive cavitation detectors, get quotes for acoustic kit
    19 
    20 
    21 **Present:** Ben Cox, Emma Harris, Ken Long, John Matheson, Colin Whyte
    22 
    23 __// Discussion: //__
    24 KL described using an analytical approximation (Batfield 1997) to model the energy deposited by 15MeV protons in water and calculate the Bragg peak dimensions. Taking the speed of sound to be 1481 m/s then the time taken for a sound wave to travel the PFWHM is 50ns ( characteristic frequency 20MHz). BC commented that this fits with photoacoustic experiments in which the pulse length is near 10ns to ensure stress confinement. Compared to likely test beams, LhARA aims at 10-40ns bunch length, AVO uses 5-10ns bunches in a train, CERN or cylclotrons would be longer.
    25 
    26 EH brought up potential problems with energy deposited in the material of the cuvettes holding the cell culture, leading to energy loss and generation of unwanted acoustic signals. It may be necessary to have a special cuvette or well plate design. BC noted that breast imaging may provide an example of how to do this.
    27 
    28 A discussion was held about what the transducer (or transducer array) might look like. Transducers are 1mm – 20 mm in size typically, with bigger being more sensitive but also more directional (less good for imaging). A good approach could be to start with a single fairly large transducer on axis. Different transducers could be compared and an array could be synthesized by mechanical motion.
    29 Shaped transducers are available which have a distinct focal length. BC comments that we have to try this empirically – historically, simulations have reproduced the frequency spectrum OK but there has been significant difference between predicted and measured amplitude. EH suggested also looking at passive cavitation detectors.
    30 
    31 In terms of costs an individual transducer is order £100. Readout is expensive – Verasonics (https://verasonics.com/about-verasonics/) do a 256 channel system for circa £110K. It was agreed that we should bid to buy one of these for LhARA as it will save on effort and add credibility. The system is essentially a rack of digitisers.
    32 
    33 We may also be able to request funding (£10K - £205K) for equipment from https://www.ukri.org/opportunity/early-technology-development-and-equipment-for-stfc-grant-holders/ Closing date 27th Oct.
    34 
    35