APP-VII Introduction to Astro-Particle Physics. Maarten de Jong

Transcription

1 APP-VII Introduction to Astro-Particle Physics Maarten de Jong 1

2 High-energy neutrino astronomy How to build a km 3 detector in the sea

3 1960 Markov s idea: Use sea water as target/detector ν µ + N µ + X Range of muon Detect Cherenkov light Transparency of water R 1 km at 00 GeV 90 A N sin θc cm π d λ m 3

4 muon energy loss de/dx [MeV g -1 cm ] Ionisation Bremsstrahlung (+ ) Energy [GeV] critical Energy Bremsstrahlung e + e - stochastic processes Ionisation 00 MeV / m (1 g / cm 3 ) ~constant 4

5 muon range E 0 de dx = 00 MeV m Bremsstrahlung + E(x) 0 0 x E 0 average range m 00 MeV 5

6 muon range in water range [km] Bremsstrahlung + Ionisation Energy [GeV] de = a + be dx dx = 1 de a + be 0 R = 1 ln( a be ) + b E = a+ be a 1 ln( 0 ) b 6 0

7 muon range in water (II) km muon neutrino interaction detector effective volume instrumented volume 7

8 Huygens principle Cherenkov effect v = c/ n muon v= βc muon β c < c n Threshold effect βc c n index of refraction n= n( λ) n 1.3 visible light 8

9 Cherenkov angle muon θ t cβ cosθ c = 1 n( λ) 9

10 Energy threshold velocity β 1 n n 1.3 γ n n 1 Energy E 1.5 m c 1GeV µ 10

11 Cherenkov light yield charge of particle d N πα Z 1 = 1 dλdx λ n β number of photons unit track length unit wavelength index of refraction velocity of particle β 1 = πα sin λ θ c 11

12 Energy loss de dx λ = min d N hc d λ dλdx λ n( λ) n = hc πα sin θc d λ 3 λ λ min λ min MeVm n(70 nm) MeV m Ionisation 1

13 Arrival time of light t muon θ d β 1 t 0 l s cosθ = 1 n t = t ( l d ) + n d c tanθ c sinθ l+ dtan( θ ) = t s 0 + = t c 0 + c 13

14 Arrival time of light (II) t d = 1 nd + 1 θ c θ tanθ c θ sinθ d 1 ncosθ = c sin θ = 0 t d 1 ncosθ = θ c θ sin θ 3 cosθ = 1 n dnsin θ (1 ncos θ)sinθcosθ = > 0 4 c sin θ minimum 14

15 Arrival time of light (III) muon θ c timing accuracy ~ns 15

16 photon detection QE(λ) photo-multiplier tube (PMT) Ω A e ~50 cm pressure resistant glass sphere 16

17 A = πd sinθdx muon dx θ c d N = dn dx dx A PMT A A= A PMT = QE 764 sin θc APMT dx cm πd sinθ dx c = QE 764 A sin θc cm PMT π d 17

18 Absorption of light in sea water Smith & Baker absorption length [m] Measurements ultra violet wavelength [nm] red 18

19 Light absorption (II) dn dx N absorption length N( x) = N(0) e x / λ Nd ( ) = I 0 e d / λsinθ π d c N 90 A sin θc cm π d e d / λ sinθ QE, absorption, etc. 19 max c

20 Neutrino interactions 0

21 reminder e' Sun ~ MeV ν e e θ e ν e ' sin θe mc e E e ' Kamiokande (solar) neutrino telescope 1

22 reminder (II) µ ν µ > GeV W q u q d q q q u q nucleon quark-gluon sub-structure Deep Inelastic Scattering

23 kinematics p p 1 q = p1 p nucleon x P n P n struck quark elastic scattering on a quark 3

24 brick wall q W quark x P n -x P n Energy-momentum conservation q = xpn q = xp q n x momentum fraction of nucleon carried by struck quark Lorentz invariant Björken Q ν q P q n Mc n x n Q = M c ν 1 4

25 nucleon structure u d u small Q QCD evolution q(x) q q q u q q d u q large Q q q q q q q u q q q d u q q very large Q 0 ⅓ 1 x Q wavelength of microscope 5

26 reminder Weak interaction left-handed fermions h = 1 anti-fermions h = +1 6

27 cross sections p q q quark = fermion p 1 x P n σν ( q) 1 y q Pn q xpn = p P p xp 1 n 1 n 0 y 1 ( y) σν ( q) 1 7

28 cross section cross section [cm ] σν ( µ n) σν ( µ n) Left handedness of weak interaction very large Q qx ( ) qx ( ) Energy [GeV] 8

29 p 1 p θ q= p1 p nucleon at rest = detector frame ν µ m c, m c E, E µ 1 = Q ( p p EE p p cos θ ) = EE (1 cos θ ) 1 θ 4EE 1 sin 9

30 detector frame Kinematics y q P p 1 n P n ν q P M c n n Physics Q 4 sin θ EE 1 y = E 1 E E 1 ν = = E ye 1 1 E n Q = M c ν x θ M c n 1 y E 1 y x 30

31 median ν µ scattering angle Numerical calculation nota bene: E increases angle [deg] Q x increases decreases Energy [GeV] δθ decreases Measure direction of muon neutrino telescope 31

32 Antares neutrino telescope 3

33 ~00 persons 6 countries ~40 km off the coast near Toulon 1 lines ~.5 km 500 m 50 Atm. ~00x00 m 33 5 storeys / line

34 1 x 5 = 300 detection units 10 PMT photon detection Optical beacon timing calibration Electronics readout Hydrophone acoustic positioning ~1 m titanium frame 34 mechanical support

35 Muon detection causality 35

36 reminder (same observer, events) line element ds = c dt dx dy dz ds > 0 ds < 0 cdt > dx cdt < dx causally connected causally disconnected 36

37 reminder (II) light like separations ds = 0 ds > 0 time like separations ds < 0 space like separations 37

38 same event, observers c dt n dx causally connected x c n hit 1 t hit (1,3) and (,3) are causally related, but not hit (1,) hit 3 hit hit detected photon at position x and time t 38

39 Accidental coincidences background 39

40 number of sources count rate time window ( N ) ( ) Rm ( ) f f T m m 1 number of coincidences m N m 1 f ( f T) m! 1 = m! F p ( Nf) ( N f T ) m 1 Total rate Probability 40

41 directional information muon ~km z 1 z R λ abs ( z z ) R tan θ ct ( t ) ( z z ) + R tanθ 1 c 1 1 c 41

42 directional information (II) R 1 m! Nf ( N f T) m 1 L λabs T =± ± µ s ± ± 50ns c/ n c/ n N = 900 (300) ~ 45 ( 15) f = 100 (1) khz 100 (1) khz () local coincidences (and large pulses) 4

43 multi-directional trigger Field of View = δ Ω θ N δ = 4π Ω 00 ϕ 1 R' N ( 0.01) m R R 43

44 multi-directional trigger (II) effective volume [m 3 ] majority (other) multi-directional 10 log(e ν ) 44

45 coincidences between PMTs 40 K 40 Ca + e - 1γ number of coincidences t [ns] e - 40 K 40 Ca + e - γ 45

46 coincidences between floors data Monte Carlo muon direction muons Rate [Hz] t [ns] 46

47 coincidences between floors (II) muons Rate [Hz] N 1 N < N 1 depth [m] stopping (atmospheric) muons 47

48 Reconstruction principle t θ c d 0 t l t = t ( l d ) + n d c tanθ c sinθ c medium properties c δx = 0 cm δt = 1 ns δθ = 0. deg. 48

49 Neutrino effective area A σ R very small E? Area [m ] θ zenith angle: integrated 0-30 degrees degrees degrees 10 log(e/gev) 49

50 Neutrino propagation trough Earth probability θ neutrino absorption Energy [GeV] 50

51 Angular resolution muon neutrino δα [deg] scattering angle 10 log(e/gev) 51

52 Status of Antares 5

53 Muon signature Cherenkov light ns 1 z shower shower Cherenkov light t muon detector signal 53

54 EM-showers (II) line 1 line 1 line 3 line 4 line 5 54

55 EM-showers (III) Monte Carlo data Rate [Hz] Number of showers 55

56 Composition of cosmic rays Iron proton 56

57 EM-showers (IV) Fe p data Rate [Hz] Number of showers 57

58 Neutrinos Antares Atm. muons Atm. neutrinos Atm. total number of events ~1000 neutrinos! muon θ D =.5 km d(θ ) cos(θ) Earth 58

59 Neutrino sky map No point sources found yet 59

60 Gamma-Ray Burst All data detector alert location of GRB save analysis All data before, during and after GRB 60

61 Result Gain in size E ν [GeV] 61

62 Evolution 1 st generation pre-prototypes nd generation 3 rd generation Dumand Baikal Nestor Nemo Amanda Antares IceCube KM3NeT present future 6

63 KM3NeT camera 31 x 3 PMT 3 x 10 PMT light concentrator ring increase of photo-cathode area by 0 40% 63

64 Neutrino astronomy has become possible Let s go and explore it 64

65 Neutrinos, they are very small. They have no charge and have no mass And do not interact at all. The earth is just a silly ball To them, through which they simply pass, Like dust maids through a drafty hall Or photons through a sheet of glass. They snub the most exquisite gas, Ignore the most substantial wall, Cold-shoulder steel and sounding brass, Insult the stallion in his stall, And scorning barriers of class, Infiltrate you and me! Like tall And painless guillotines, they fall Down through our heads into the grass. At night, they enter at Nepal And pierce the lover and his lass From underneath the bed - you call It wonderful; I call it crass. John Updike 65