VO Detector and detector systems for particle and nuclear physics I. Friday

Transcription

1 VO Detector and detector systems for particle and nuclear physics I johann.zmeskal@oeaw.ac.at Friday Detector 1

2 PARTICLE DETECTION Particle cannot be seen or measured directly Only the result of an interaction with matter will be observed. In the end, everything is converted to optical pictures electric signals 2

3 Particle Detection Principle The detection of particles happens via their energy loss in the material it traverses... Charged particles Ionization, Bremsstrahlung, Cherenkov... Hadrons Photons Neutrinos Nuclear interactions Photo, Compton effect, pair production Weak interactions 3

4 LBNL Image Library Measurement of Particle Properties Charge direction Momentum B, radius q B R mv Lifetime measurement of path length Velocity time of flight (TOF) p Discovery of the Positron 1932 Carl Anderson, Noble Prize

5 DETECTOR TYPES Scintillation detectors Semiconductor detectors Gaseous detectors Calorimeter ECAL: Electromagnetic calorimeter HCAL: Hadronic calorimeter Tracking detectors (tracks momentum, charge, decay) Multipurpose detectors / high precision experiments combination of different detectors (FAIR PANDA) 5

6 The ideal particle detector should provide end products charged particles neutral particles photons coverage of full solid angle (no cracks, fine segmentation) measurement of momentum and/or energy detect, track and identify all particles (mass, charge) fast response, no dead time practical limitations (technology, space, budget)! Detector 6

7 Detector systems number of particles event topology momentum / energy particle identity cannot be achieved with a single detector GEOMETRY detector system Detector 7

8 Magnet concepts Solenoid B (air-core) Toroid B I magnet coil I magnet + strong and homogeneous field - massive iron return yoke - limited in size (cost) - solenoid thickness (radiation length) + large air core, no iron, less material - additional solenoid in the inner parts -- inhomogeneous field - complex structure µ µ CMS, KLOE, FOPI, PANDA ATLAS 8

9 ATLAS and CMS magnet coils CMS solenoid (5 segments) ATLAS toroid coils Autumn 2005 Atlas: D=9m; L=24m CMS: SC, 4.0T, Ø5.9m, L 12.5m 9

10 Exploded View of CMS SUPERCONDUCTING COIL CALORIMETERS ECAL PbWO4 crystals HCAL Plastic scintillator/brass sandwich IRON YOKE TRACKER Silicon micro-strips pixles Total weight : 12,500 t Overall diameter : 15 m Overall length : 21.6 m Magnetic field : 4 Tesla MUON BARREL Drift Tube Chambers Resistive Plate Chambers MUON ENDCAPS Cathode Strip Chambers Resistive Plate Chambers 10

11 Slice through the CMS detector Particle interaction and reconstruction different detectors for different particles 11

12 CMS Detectors interleaved with the magnet yoke steel layers 12

13 Collider versus fixed target Detector 13

14 Detector parameters solid angle granularity dead time / rate capability resolution efficiency material budget radiation tolerance COST!! Detector 14

15 Example for a collider and a fixed target experiment KLOE at DANE PANDA at FAIR Detector 15

16 DANE e + -e - collider Accu. Hadron

17 DANE principle operates at the centre-of-mass energy of the meson mass m = ±.008 MeV width = 4.43 ±.06 MeV produced via e + e - collision with (e + e - ) ~ 5 µb K + e + e + e e + e + e + e + e + e e e e e e e e e e K - production rate 2.5 x 10 3 s -1 monochromatic kaon beam (127 MeV/c) bremsstrahlung loss per turn ~ 14 kev 17

18 About strange particles The quark eigenstates are: K 0, K 0 The CP eigenstates are: K 1 K 0 + K 2 0, K 2 K 0 K 2 0 M. Gell-Mann A. Pais

19 The KLOE Detector Detector 19

20 The KLOE Detector Drift chamber Electromagnetic calorimeter Interaction region Superconducting coils Iron yoke Detector 20

21 Detector 21

22 Detector 22

23 KLOE calorimeter

24 KLOE calorimeter density ~ 5.0 g/cm 3 total length of fibres ~ km read out by ~ 5000 mesh PM SiPMs

25 Determination of the neutral kaon mass, by measuring 4 gammas 0 K s Photon energy resolution (E)/E = 5.7%xE(GeV) -1/2 time resolution t/t = 54 [ps]xe(gev) -1/2

26 Neutron detection efficiency MC simulation, confirmed with measurements at TSL (Uppsala) Threshold at 1 MeV Threshold at 3 MeV

27 PANDA FAIR Anti-Proton ANnihilation at DArmstadt Detector 27

28 Facility for Antiproton and Ion Research Detector 28

29 Physics goals of PANDA Study the strong interaction with antiprotons Particle physics Hadron physics Nuclear physics Questions... Mechanism of confinement? Inner structure of hadrons? Origin of mass and spin (macroscopic properties)? Exotic colour neutral objects? Detector 29

30 Physics goals of PANDA Hadron Spectroscopy Experimental Goals: mass, width & quantum numbers of resonances Charm Hadrons: charmonia, D-mesons, charm baryons to understand new XYZ states, D s (2317) and others Exotic QCD States: glueballs, hybrids, multi-quarks Spectroscopy with Antiprotons: Production of states of all quantum numbers Resonance scanning with high resolution Detector 30

31 Physics goals of PANDA Nuclear Physics Charm in the Medium Mesons in nuclear matter Masses change in nuclei D-mass lower Lower D D threshold J/ψ absorption in nuclei Hypernuclei 3rd dimension in nuclear chart Double hypernuclei production via Ξ - capture Λ Λ interaction in nucleus Other topics Short range correlations Color transparency Detector 31

32 Detector 32

33 Physics goals of PANDA Hadron Structure Generalized Parton Distributions Formfactors and structure functions Timelike Nucleon Formfactors Drell-Yan Process full PWA or polarized beam/target PANDA Physics Report www-panda.gsi.de Detector 33

34 Detector 34

35 PANDA - detection concept Detector 35

36 HESR High Energy Storage Ring Up to stored antiprotons Beam momentum: ( ) GeV/c Phase-space cooling Fixed internal target Electron cooler Stochastic cooling Stochastic cooling Injection Operation modes a) High luminosity: L = cm -2 s -1 p/p 10-4 b) High resolution: L = cm -2 s -1 p/p Detector 36

37 The PANDA Spectrometer TARGET SPECTROMETER FORWARD SPECTROMETER Solenoid Target Muon ID Dipole Drift Chambers DIRC Muon Range System Vertex Central Tracker Electromag. Calorimeters RICH Detector 37

38 PANDA - Solenoid Superconducting magnet Central field: B = B z = 2 T High field homogeneity: 2% Dimensions inner bore: 1.9 m / length: 2.7 m Coil and cryostate Laminated layers for muon range system Iron flux return yoke z beam axis Target pipe warm hole Outer yoke dimension: 2.3 m / length: 4.9 m Total weight: ~ 300 t 38

39 PANDA Dipole magnet Superconducting magnet Field integral (bending power): 2 Tm Deflection of antiprotons with p =15 GeV/c: 2.2 Bending variation: 15% Vertical acceptance: 5 Horizontal acceptance: 10 Total weight: 200 t Forward tracking detectors partly integrated 39

40 PANDA Target system ~ 2 m Target production (VP) Target pipe Injection point (VP) Beam pipe Primary target setup Appropriate cut-outs in solenoid magnet Vacuum pumps (VP) (VP) Target dumping system Beam-target cross Design compatible with all different options 40

41 The new INFN-SMI-GSI cluster jet

42 Cluster-jet nozzle at GSI max = 1, atoms/cm 2 (29,7 K and 15 bar)

43 PANDA Tracking Micro-Vertex Detector Target spectrometer Outer tracker GEM stations Forward spectrometer Straw-tube layers Central tracking (Helix fit) Forward tracking (Straight lines) 43

44 PANDA Micro Vertex Detector Design of the MVD 4 barrels and 6 disks Continuous readout Inner layers: hybrid pixels (100x100 µm 2 ) Outer layers: double sided strips: Rectangles & trapezoids NXYTER readout Mixed forward disks (pixel/strips) Challenges Low mass supports Cooling in a small volume Radiation tolerance PhiPsi2011 BINP, Novosibirsk 44

45 PANDA Central tracker Central Tracker σ rφ ~150µm, σ z ~1mm δp/p~1% (with MVD) Material budget ~1% X 0 Straw Tube Tracker 27 µm thin mylar tubes, 1 cm Ø Stability due to 1 bar overpressure GEM Time Projection Chamber Continuous sampling GEMs to reduce ion feedback Online track finding Forward GEM Tracker Large area GEM foils Ultra thin coating 45

46 PANDA Straw tubes Detector Layout 4500 straws in layers Tube made of 27 µm thin Al-mylar, Ø=1cm R in = 150 mm, R out = 420 mm l=1500 mm Self-supporting straw double layers at ~1 bar overp.(ar/co 2 ) Material Budget Max. 26 layers, 0.05 % X/X 0 per layer Total 1.3% X/X 0 Detector performance r/ resolution: 130 µm z resolution: ~ 1 mm Prototype test at COSY-TOF 46

47 The PANDA Detector - GEM-TPC Detector 47

48 PANDA Particle IDentification PANDA PID Requirements: Particle identification essential Momentum range 200 MeV/c 10 GeV/c Different processes for PID needed PID Processes: Cherenkov radiation: above 1 GeV Radiators: quartz, aerogel, C 4 F 10 Energy loss: below 1 GeV Best accuracy with TPC Time of flight Problem: no start detector Electromagnetic showers: EMC for e and γ 48

49 PANDA Cherenkov detectors Target spectrometer Forward spectrometer Barrel DIRC Disc DIRC RICH D etection of I nternally R eflected C herenkov light R ing I maging CH erenkov detector Radiator material: Fused silica 3 /K separation 0.8 GeV/c p 5 GeV/c Radiator materials: Aerogel / C 14 F 10 /K separation 2 GeV/c p 15 GeV/c PhiPsi2011 BINP, Novosibirsk 49

50 PANDA Calorimeter Target spectrometer Forward spectrometer Barrel EMC Endcap structures Shashlyk calorimeter Operated at -25 C ~ 15,000 cristals Cristal: PbWO 4 Lead-scintillator sandwiches 351 modules (13 rows / 27 columns) 50

51 PANDA PWO Crystals PWO is dense and fast Low γ threshold Increase light yield: - operation at -25 C (4xCMS) Challenges: - temperature stable to 0.1 C - control radiation damage - low noise electronics Delivery of crystals started PANDA Calorimeter Barrel Calorimeter PWO Crystals LA-SiPM readout, 2x1cm 2 σ(e)/e~1.5%/ E + const. End cap 4000 PWO crystals High occupancy in center LA-SiPM or VPT PhiPsi2011 BINP, Novosibirsk 51

52 PANDA Time-of-flight systems Target spectrometer Barrel tile hodoscope Forward spectrometer Scintillator wall SiPM Scintillator Time resolution: ( ) ps Scintillator slabs or pads of multigap resistive plate chambers (RPC) Quad module Scintillator slabs Time resolution: ~ 50 ps 52

53 Detector arrangement Detector 53

54 Cross section Detector 54

55 Cross section Detector 55

56 Luminosity Detector 56

57 Interaction with matter hadron compton photoeff pair rad coll tot dx de dx de dx de dx de dx de dx de dx de 57

58 58 Interaction of particles with matter hadron compton photoeff pair rad coll tot dx de dx de dx de dx de dx de dx de dx de some examples

59 Bethe-Bloch Formula (Relativistic) charged particles other than electrons lose energy in matter primarily by ionization and atomic excitation. The mean rate of energy loss (or stopping power) is given by the Bethe-Bloch equation: de dx Z z 2m e v Tmax N r m c 2 2 a e e ln A I 2N a r m c [ MeVcm e e g ] C Z mean excitation potential I (10eV ) Z T max head-on or knock-on collisions T max 1+ 2 m M e 2m c e m ( M e ) 2 Hans Bethe Felix Bloch Detector 59

60 Mean excitation energies ICRU - International Commission on Radiation Units and Measurements Detector 60

61 Energetic knock-on electrons ( - rays): The distribution of secondary electrons with kinetic energies T >> I is given by: For example: 2 d N dtdx 1 2 for I<<T T max Kz 2 Z A 1 2 F( T) 2 T for a 500 MeV pion on a silicon detector with thickness x = 0.3mm, on average one -ray (with 12 kev) is produced per particle crossing integrating above Eq. from Tcut(=12 kev) totmax on average ray (with 116 kev) are produced per particle integrating Tcut (=116 kev) to Tmax (116 kev is the mean energy loss in 0.3mm silicon for MIPs) Detector 61

62 Mean energy loss rate Z/A=1 Z/A~0.5 kinematical term 1/β 2 MIPs ~3-4 relativistic rise ln(β 2 2 ) Detector 62

63 Energy loss of muons Fermi-plateau Detector 63

64 Summary Bethe-Bloch BB valid for heavy particles ( m>~m µ ) mean energy loss de/dx normally given in MeVcm 2 /g de/dx independent of the mass of the projectile Energy transfer within I < de < T max (I...mean excitation energy ~ 10 Z ev) Detector 64

65 Mean range - range straggling The range can be determine by passing a beam of particle with the desired energy through different thicknesses of the material in question and measure the ratio of transmitted to incident particles. Detector 65

66 Bragg curve and mean range The energy loss of a charged particle passing an absorber is rising, most of the energy is deposited at the end (important for radiotherapy) intensity as function of x Energy loss per length unit Bragg peak Integration of the Bethe-Bloch formula gives the mean range <R>: R 0 E dx de de Detector 66

67 Range of charged particles in matter R...mean range M...mass of projectile Detector 67

68 Interaction of charged particles Real detectors (limited granularity) can not measure <de/dx>! In a detector the deposited energy ΔE in a layer of finite thickness x is measured. For thin layers or low density materials: Few collisions, some with high energy transfer Energy loss distributions show large fluctuations towards high losses: Landau tails For thick layers and high density materials: Many collisions Central Limit Theorem, Gaussian shaped distributions Detector 68

69 Energy loss of electrons and positrons Like heavy particles electrons and positrons also suffer collisional energy loss when passing through matter. But also, because of their small mass, an additional energy loss mechanism comes into play: the emission of electromagnetic radiation arising from scattering in the electric field of the nucleus (bremsstrahlung). de dx tot de dx rad + de dx coll Classically: bremsstrahlung can be explained as deviation of the electron from its straight-line caused by the electric attraction of the nucleus field. Detector 69

70 Collision loss For electrons the Bethe-Bloch formula has to be modified: the assumption that the incident particle remains un-deflected during the collision process is not valid (due to the small e mass) for electrons the collisions appear between identical particles, therefore their indistinguishability has to take into account de dx Z 1 ( + 2) N are mec ln + F( ) A 2( I / mec ) 2 2 C Z with the kinetic energy of the incident electron/positron in units m e c 2 F( ) 1 ß / 8 (2r + 1)ln 2 2 ( + 1) for electrons ß F( ) 2ln ( ( + 2) + 10 ( + 2) ( + 2) 3 ) for positons Detector 70

71 Energy loss by radiation - Bremsstrahlung At energies below a few hundred GeV electrons and positrons are the only particles for which radiation contributes substantially to the energy loss of the particle. e.g. for muons (m = 106 MeV) the radiation loss is ~ times smaller than for electrons 71

72 Energy loss of electrons in copper Detector 72

73 Radiation length Is defined as the distance over which the electron energy is reduced by a factor 1/e due to radiation loss: de E N rad dx E E 0 e x / X 0 x...travelled distance X 0..radiation length Detector 73

74 Interaction of photons The behaviour of photons in matter is quite different from that of charged particles, as photons have no electric charge there are no inelastic collisions with atomic electrons. The main interactions of X-rays and -rays in matter are: photoelectric effect Compton scattering pair production 74

75 Photoelectric effect The photoelectric effect involves the absorption of a photon by an atomic electron and the subsequent ejection of the electron from the atom. The energy of the outgoing electron is : Photoelectric cross section for lead E = h - B.E. Detector 75

76 Compton scattering Klein-Nishina formula used to calculate Compton scattering cross section scattering on a quasi-free e - Energy distribution of Compton recoil electrons Compton edge Detector W.R. Leo, Techniques for Nuclear and 76 Particle Physics Experiments

77 Pair production The process of pair production involves the transformation of a photon into an electron-positron pair. In order to conserve momentum, this can occur only in the presence of a third body (e.g. nucleus). pair production cross section in lead for : E m c 2 e E pair,nucl 2m c 1 1 / 3 Z E 4 re Z ln 2 9 mec e for : E / 3 mec Z pair,nucl 4 re Z ln 1 / 3 9 Z 1 54 W.R. Leo, Techniques for Nuclear and Particle Physics Experiments Detector 77

78 Total photon absorption cross section in lead Photoelectric effect Z 4 to Z 5 E -3.5 to E -1 Compton scattering Z E -1 Compton Pair production Z 2 ln E pair photoelectric W.R. Leo, Techniques for Nuclear and Particle Physics Experiments Detector 78

79 The photon mass attenuation length I I0 exp( t / ) Detector 79

80 Interaction of neutrons Detector 80

81 Interaction of neutrons 81