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Study of the acoustic field generated by the electron beam in water. Olga Ershova July, 19 th 2006 INFN Genova. Acoustic neutrino detection. Proposed in 1957 Detection of acoustic signals produced by neutrino-induced showers in water E > 10 15 eV. 2 / 24.
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Study of the acoustic fieldgenerated by the electron beam in water Olga Ershova July, 19th 2006 INFN Genova
Acoustic neutrino detection • Proposed in 1957 • Detection of acoustic signals produced by neutrino-induced showers in water • E > 1015 eV 2 / 24
Two methods of neutrino detection Cherenkov detection: Light attenuation length~ 20-40 m Acoustic detection: Sound attenuation length ~ 1 km Large effective volume of the detector is achievable with reasonable number of acoustic sensors 3 / 24
Thermal mechanism of sound generation in water µ Neutrino produces а hadronic shower Heat release localizedalong the shower Instant volume expansion Pressure wave νµ 4 / 24
d = 20 cm Energy deposition area(for E = 1020 eV): L = 20 m Area of signal propagation: 5 / 24
1. 2. Bipolar shape Frequency range E > 1015 eV:f = 1 - 100 kHz E = 1020 eVhadronicshower Max = 10 kHz Acoustic signal characteristics 6 / 24
Acoustic experimentson the accelerators • Brookhaven NL, Harvard (1979) • ITEP (2004) • INR (1987) • MSU SINP (2006) The only way to study acoustic effects from particle showers are the accelerator experiments in intense beams of protons and electrons protons electrons 7 / 24
MSU electron accelerator 9 / 24
MSU electron accelerator(RTM-70) 10 / 24
Modeling • Proton beam(d = 2 cm, E = 200 MeV, N = 4·1010) • Electron beam(d = 4 mm, E = 50 MeV, N = 9·1010) 11 / 24
Mean energy loss per path length unitof protons and electrons in water dE/dZ, MeV/mm Z, mm 12 / 24
Mean energy loss per unit of volume Protons X, mm Energy loss, MeV/mm3 Z, mm 13 / 24
Mean energy loss per unit of volume X, mm Electrons Energy loss, MeV/mm3 Z, mm 14 / 24
Transverse distribution of energy loss for several beam cross-sections Electrons Протоныбез коллиматора 15 / 24
Experimental set-up Y Y hydrophone hydrophone 523mm 46 mm beam Z X 945 mm 508 mm 16 / 24
Acoustic Basin 100x50x50 cm3 Scanner(step = 4.5 mm) Beam pipe beam 17 / 24
Points of measurement • 6 linear tracks:I,II,III,IV along the beam axis, V,VI - across. • I,II,III,IV: 100 points;V,VI: 40 points. • The step is equal to 4.5 mm. 19 / 24
Electric diagram 50 dB 20-200 kHz Amplifier 1 hydrophone 10 dB 10- 100 kHz Amplifier 2 Beam current transformer • Observation time: 1 ms • Digitization frequency: 10 MHz • 650 oscillograms recorded computer Oscilloscope 20 / 24
Recorded acoustic signal(x = 6 cm, step 10) Hydrophone 40 µs, R=6 cm Beam currenttransformer 21 / 24
Beam current calculated for each measurement Signals normalized to 1 mA beam current Plotted one under anotherwith 1 step distance between them 22 / 24
beam beam Space-time structureof the acoustic field (x = 6 cm) Signal from the area of beam entrance Signal from the beam point closest to the hydrophone Z = 40 cm hydrophone Z = 0 cm X = 6 cm X 23 / 24
beam Space-time structureof the acoustic field (z = 20 cm) X = 30 cm Z hydrophone X = 0 cm Z = 20 cm 24 / 24