Radar for Salt Ultra-High-Energy Neutrino Detector and Contribution of W-Gluon Fusion Process to Collision of Neutrinos against Quarks

Transcription

1 Radar for Salt Ultra-High-Energy Neutrino Detector and Contribution of W-Gluon Fusion Process to Collision of Neutrinos against Quarks Masami Chiba, Yoko Arakawa, Toshio. Kamijo, Fumiaki Yabuki, Osamu Yasuda, Yuichi Chikashige*, Keisuke Ibe*, Tadashi Kon*, Yutaka Shimizu*, Yasuyuki Taniuchi**, Michiaki Utsumi**, and Masatoshi Fujii*** Tokyo Metropolitan University, Seikei University*, Tokai University**, Shimane University*** Talk at ARENA2008 June 27, 2008

2 UHE Neutrinos Originate in UHE Cosmic Rays & CMB Cosmic ray energy spectrum Log E(dN/dE) [km -2 yr -1 (2π sr) -1 ] Hireso group observed Greisen-Zatsepin-Kuzmin(GZK) cutoff. Abbasi et al., PRL 100, (2008) Galactic GZK threshold Log E [ev -1 ] GZK ν The energy exceeds production threshold. (CMB) GZK neutrino flux is as low as 1[/km 2 /day]. Need a huge mass of detection medium M.Chiba_ARENA

3 Attenuation length of radio wave for electric field in rock salt L/m m Synthetic Hippel TM020 tanδ= Asse tanδ= GHz_Synthetic 0.3GHz_Hockley 0.3GHz_Zuidwending 0.3GHz_Asse 0.3GHz_Heilbronn 1.0GHz_Synthetic 1.0GHz_Hockley 1.0GHz_Zuidwending 1.0GHz_Asse 1.0GHz_Lugansk 0.15GHz_Hockley_in_situ 0.3GHz_Hockley_in_situ 0.44GHz_Hockley_GPR 0.75GHz_Hockley_in_situ 2.34GHz_Synthetic_TM020 Hippel_10MHz Hippel 25GHz 1 Hippel Frequency/GHz M.Chiba_ARENA2008 3

4 Radar method: microwave reflection experiment UHEν shower Emitting antenna Rock Salt Radio wave Receiving antenna Lower frequency is available compared with Askaryan method. Brilliance of X ray source Electromagnetic ionization in rock salt generated by X ray irradiation X ray Spectrum: white Energy: kev Repetition: 800 khz Pulse width: 30ps Synchrotron radiation from KEK AR electron accumulation ring Electron energy: 6.5GeV Current: 60mA Lifetime 10 hours Brilliance [photon/sec/mrad^2/0.1%bw] PF-AR bend (60mA) E E E E E+06 M.Chiba_ARENA E+16 1E+15 1E+14 1E+13 1E+12 1E+11 photon energy [ev]

5 Experimental setup with X ray disc shutter X ray and microwave (9.4 GHz, 10-4 W) are irradiated to a rock salt sample, simultaneously. Null detection method is employed for detecting minimal signal. Measure microwave reflection change due to X ray irradiation. Rotary X ray disc shutter Lead: 4mm t Φ:100mm, Orifice: 4x4mm 2 shutter X ray Synthesized rock salt mm 3 X ray microwave M.Chiba_ARENA2008 5

6 10-13 /W Reflected power vs. elapse of time Irradiation of 1s Decay time τ=8 s Receiver: Ueda-NEC Co. Ltd.: NRG-98 Logarithmic amplification: Receiving power range; W 9.4GHz, Band width: 3MHz Elapse of time/s Microwave reflection rate of 10-6 at the X ray energy deposit of ev/s. Reflection target candidates: free electrons, local thermal blobs, color centers, phonons, polarons, polaritons? M.Chiba_ARENA2008 6

7 Coherency of the reflection Reflection Power: P X ray intensity dependence Complete coherence P (intensity) 2 (AR beam current) 2 P(40mA) =41.7±7.9 [10-13 W] P(60mA) =84.6±0.5 [10-13 W] Irradiation time dependence I=40mA P [10^-13W] beam current[ma] P(40mA) 40 = 0.49 ± 0.09 = P(60mA 60 X=1.8±0.4 x P=At X +B X=2.1±0.1 P (intensity) 2 (Irradiation time) 2 Coherent M.Chiba_ARENA2008 7

8 Temperature dependence of reflected power 3.0E-09 Power/W vs.irradiation time/s Reflection Power Temperature of rock salt (Chromel vs. Alumel thermocouples) Power/W 2.5E E E E-09 Temperature_normalized Power, quadradic fitted Temperature_linear fitted E-10 Irradiation time/s 0.0E E Irradiation time/s Power/W vs. irradiation time/s Power/W 3.0E E E E E E E Irradiation time/s Chromel vs. Alumel thermocouples Rock salt(2mm 2mm 10mm) X ray M.Chiba_ARENA2008 8

9 Temperature dependence of reflected power J. C. Owens, Phys.Rev. 181(1969)1228 ε =6860/(1980-T) n= ε Reflected power (n-1) 2 /(n+1) 2 Temperature Energy deposit Irradiation time ε' vs temperature Surface reflection ΔT=0.01 ΔP=10-6 Reflection power vs temperature ε' Refrection power T, T, M.Chiba_ARENA2008 9

10 Coherent reflection of radio wave Increase of temperature in bulk does not explain the coherent reflection. Coherency: Reflected power Square of energy deposit At the beginning of irradiation, local thermal blobs are generated. local thermal blob X ray Rock salt sample (2mm 2mm 10mm) Coherent reflection M.Chiba_ARENA

11 Rock salt vs. ice as reflection media Δε /10 Heat capacity mj/(mole K) Thermal conductivity W/(m K) Rock salt (20 ) Ice (-30 ) Radio attenuation length of Antarctic ice is as long as natural rock salt. Ice could reflect radio wave if the reflection at rock salt is due to local thermal blobs. The reflection rate may be less than rock salt due to smaller permittivity change and larger heat capacity. The smaller thermal conductivity is favorable. Enormous Antarctic ice becomes available if the reflection is verified. M.Chiba_ARENA

12 Radar method: Minimum setup Need no expensive boreholes. Utilize low frequency radio wave around 10MHz where attenuation length is expected as long as 7000m. Minimum setup can only count # of neutrinos. Increased receiving antennas help to determine the shower axis without directional information. Reflection efficiency is different with the angle to the antenna. Up going UHE neutrinos are absorbed by the earth. Plane antenna on the surface(10mhz) ν Minimum setup Surface of the earth Excavated space Emission Reflection Salt dome 6m 6cm 6m Shower Electrode Rock salt 6cm 10m 10m M.Chiba_ARENA

13 Receiving power vs. Range Rock Salt Emitting antenna UHEν Electromagnetic shower S Γ R=3000m P e =1GW Receiving antenna P r Attenuation length in rock salt: L=7000m@ 10MHz Energy 2 =(exp(-6000/7000)) 2 =0.18 Energy reflection rate:γ=10-6 (10-19 E) 2 =10-6 (Shower energy: E=10 19 ev) S1 S2=1 m 2 : radio wave cross sections of shower and antennas P e =1GW: Peak power of radar Receiving power:p r =P e α Γ S 1 S 2 (4πR 2 ) -2 = W M.Chiba_ARENA

14 Effective volume of rock salt for radar Surface of the earth E:Shower energy Γ:Reflection efficiency R: Rage of radar Radar power: 1GW(Peak Power) 10MHz Receiving power > W Excavated space E(eV) Γ R/m ν Emission Shower Reflection R Salt dome Effective volume 2πR 3 /3 M.Chiba_ARENA

15 UHE neutrino cross section with W-gluon fusion process W-gluon fusion process Feynman automatic calculation program, GRACE Characteristics: tree & 1 loop; any # of initial and final bodies CTEQ6 proton structure function Studied by Yuichi Chikashige, Keisuke Ibe, Tadashi Kon M.Chiba_ARENA

16 Structure function of proton Structure function of Q^2=5GeV^2 xf(x) 1.00E E E E E E E E-05 c c-bar s s-bar d d-bar u u-bar g 1.00E E E E E E E E E+0 0 x M.Chiba_ARENA

17 Charged current cross section, Q 2 >5GeV 2 νe + N e + X (CC) 1.E+06 1.E+05 no W-g 1.E+04 1.E+03 W-g (x>-5) σ(pb) 1.E+02 1.E+01 E=10 16 ~10 18 ev W-g (x>-8) 1.E+00 1.E-01 10^2 10^3 10^4 10^5 10^6 10^7 10^8 10^9 10^1010^1110^12 1.E-02 E(GeV) σ (W-Gluon fusion) σ(w exchange) between E=10 16 ~10 18 ev σ(total) 2σ(W exchange) M.Chiba_ARENA

18 Summary Radar method does not require expensive boreholes. # of GZK neutrinos/year is estimated by a simulation. [W exchange] + [W-Gluon fusion] processes: 6~18 GZK neutrinos/year > ev Minimum setup: # of GZK neutrinos could be counted. High peak power radar of 1GW, otherwise array antennas of lower power are needed. If the reflection is due to local thermal blobs, Antarctic ice would be utilized. Acoustic wave would be reflected in a similar way. ν Minimum setup Surface of the earth Excavated space Emission Reflection Shower Salt dome 3km M.Chiba_ARENA

19 Backup M.Chiba_ARENA

20 Incident wave length: λ Coherent scattering Targets: electrons, local thermal blobs, color center, etc. E 1 λ>>d: distance between targets d Reflection E 2 E 3 P= E 1 + E E n 2 = E E E n E i E k + =n x E i 2 P: reflected power n: number of targets t: X ray integration time If lifetime of targets is long: n t P=At x +B A, B, x: fitting parameter x: coherence parameter x=2: full coherent x=1: random phase M.Chiba_ARENA

21 Reflected power against temperature (imaginary permittivity) λ=0.029m (10.2GHz), ε'=5.9, L=2mm tanδ=ε''/ε' L=λ/(π* (ε')*tanδ) Reflection power loss: (exp(-0.002/l)) 2 B. Meng et al, Phys. Rev.B 53,(1996)12777 Power/2mm (exp(-0.002/l))^2 X ray Rock salt sample (2mm 2mm 10mm) Radio wave (Path length 2mm) Reflection power vs T Refrection power T, K M.Chiba_ARENA