Results of microphone tests in HiRadMat Collimation WG Meeting Daniel Deboy on behalf of the Collimation team, thanks to A. Masi, J. Lendaro, C. Derrez and team I. Efthymiopoulos and HRM team 1 Collimation WG Meeting

MICROPHONES AT HRM Purpose of Sound Analysis Can we (roughly) localize Impacts with correlation measures between two or more microphone signals? Sound Pressure Level -> Amplitude of pressure wave Spectral Components -> Damage/ no damage? Investigate limitations of the system (EM noise, R2E) Application: Impact detection and localization at LHC collimators! 2 Collimation WG Meeting

Microphone Positions 3 ca 6.5 m ca 13.5 m ca 25 m Downstream Upstream Collimation WG Meeting

Localization with TDOA 4 ∆T3 Mic 3 Mic 2 Mic 1 ∆T2 ∆T1 Beam impact position Beam Speed of sound c s = 343 m/s C) Reference location s ref = ∆T2 * c s = - ∆T1 * c s Estimated location s imp = s ref + (∆T2-∆T1) * c s Reference location Collimation WG Meeting

Microphone Signals 5 Typical radiation induced noise spikes during impact Peak amplitude linear dependent on beam intensity -> saturation limit at signal amplitude equal to a sound pressure level of approximately 163 dB SPL (ca 2700Pa = 3V with 10mV/Pa output sensitivity) Collimation WG Meeting

Noise from Radiation vs. Intensity 6 Mic Downstream Measurements taken during HRMT 12 experiment Extrapolated and scaled assuming 1/r 2 mitigation -> Estimate of distances needed to avoid signal overload Upper limit of Mic sensor (eq. 163dB SPL) Collimation WG Meeting

Test 1 Mic Signals 7 ca 114 ms Sensor Saturation Blue: 13.5m Downstream Green: 13.5m Upstream Red: 24 m Upstream Sound Pressure (Pa) High Intensity Shot – Spike from Radiation Time (s) Test 1: 1 Nominal LHC Equ. 3.2E12 at HiRadMat Shot on Collimator Jaw Collimation WG Meeting

Test 1 Sound 8 RMS Noise ca 70 dB RMS Noise ca 60 dB Delay ca 44 ms = 15 m Delay ca 84 ms = 28 m Peak Value ca 100 dB Peak Value ca 90 dB Delay ca 114 ms (sound lost due to sensor saturation) Sound Pressure (Pa) Sound after High-Pass Filtering (Butter 3 rd, 100Hz) Downstream Upstream PatchRack Time (s) Amp Output Sensitivity: 3.16mV/Pa Amp Output Sensitivity: 31.6mV/Pa Collimation WG Meeting

Test 1 Peak Estimate 9 Artifacts from Radiation Spike are cut for estimation of peak value. Peak value of cut signal: Ca 93 dB SPL Energy normalized to peak value! RMS Noisefloor: Reached after 0.7s Estimated Energy at expected onset (42ms): +4.6 dB Estimated Peak SPL: 97.6 dB Collimation WG Meeting

Sound Pressure vs. Intensity 10 Collimation WG Meeting Test 2: No Damage Test 1: Damage expected Test 3: Severe Damage expected

Algorithm: Localization and Damage 11 HighPass Filter Peak Detection Calculate Delay Time Calculate Magnitude HighPass Filter Peak Detection Calculate Delay Time Calculate Magnitude Estimate Location (TDOA) Estimate Impact Strength Estimate Damage Level Mic 1 Mic 2 Reference Data Collimation WG Meeting

Remarks Localization of impacts and damage estimation is possible using only two microphones for a set of collimators! Radiation induced noise spike can be used as “trigger” signal, however… …Signal to Noise Ratio is bad due to radiation spike (long distances, low gain) –Improvement: Analogue HP Filter (allows higher gain factor) –Prototype Test of optical microphone solution (-> Balthasar Fischer - TU Vienna) Next steps: –Analyze Sound Pressure vs. Distance –Find robust methods to determine Time difference of arrival (TDOA) –Derive estimate for energy of pressure wave at outer shell of collimator –Visual Inspection of HRM09 damage for reference classification (2013) 12 Collimation WG Meeting