Outline. Calorimeters. E.Chudakov 1. 1 Hall A, JLab. JLab Summer Detector/Computer Lectures http: // gen/talks/calor lect.

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1 Outline Calorimeters E.Chudakov 1 1 Hall A, JLab JLab Summer Detector/Computer Lectures http: // gen/talks/calor lect.pdf

2 Outline Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

3 Outline Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

4 Outline Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

5 Outline Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

6 Outline Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

7 Outline Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

8 Outline Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

9 What is a calorimeter? Particle detection main goal: measure 3-momenta P Magnetic spectrometers Coordinate detectors Magnetic field Charged particles (e ±, π ± etc) Magnet θ θ Bdl P Momentum resolution: σ(p)/p P (for large P) Calorimeters Detectors thick enough to absorb nearly all of the particle s energy released via cascades (showers) Neutral (γ, n) and charged particles The energy goes mainly into heat. True C. - E o (heat) Pseudo C. - O(E o ): ionization, Cherenkov light Poisson process: N e E 0, σn e = N e and σe E 1 E

10 True Calorimeters True calorimeters measure the temperature change of the absorber: T = E 0 c M ev J/eV K too low! 10 3 J/kg 1kg High particle flux History: W. Orthmann - 1µW sensitivity; 1930, with L. Meitner they measured the mean energy (6% accuracy) of β from 210 Bi W.Pauli s neutrino hypothesis. Precise beam current measurements (SLAC-1970s, JLab-2003) Ultra-cold temperatures (low C), superconductivity - new detectors for exotic particle search, like dark matter candidates.

11 Pseudo Calorimeters Pseudo calorimeters detect O(E o ): ionization, Cherenkov light History: N.L. Grigorov idea, implementation in cosmic ray studies (Pamir, 3900 m). Layers of an absorber and layers of proportional counters - counting the number of particles in the shower (calibration needed). Starting in 1960s - revolution in compact electronics affordable ADC (Analog-to-Digital Converters). New accelerators - various types of calorimeters with ADC channels. Applications detecting neutrals good energy resolution at high energies fast signals for trigger particle identification (e ± /h)

12 Muon in Medium Trajectory of 8 GeV µ in copper. The coordinates are in cm.

13 Electron in Medium Trajectory of 8 GeV e in copper. The coordinates are in cm.

14 Proton in Medium Trajectory of 8 GeV proton in copper. The coordinates are in cm.

15 e ± interactions Energy loss in medium e (E) Bremsstahlung e ± Z e ± γz Ionization Bhabha/Møller scattering e ± e e ± e e + annihilation Z Z e γ(k) de (X 1 dx 0 ) 1 E Electrons Møller (e ) Positron annihilation Bremsstrahlung e γ(k) Positrons Bhabha (e + ) σ Z 2 σµ m 2 σ e dn γ dk 1 k Ionization Lead (Z = 82) Bremsstrahlung E (MeV) de γ dk =c(k) (cm 2 g 1 )

16 Bremsstrahlung and Pair Production (X 0 N A /A) ydσ LPM /dy 10 GeV GeV TeV 10 TeV 100 TeV Bremsstrahlung 1 PeV 10 PeV y = k/e (X 0 N A /A) dσ LPM /dx TeV 10 TeV 100 TeV Pair production 1 EeV PeV 100 PeV 10 PeV x = E/k

17 σ coherent γ interactions Cross section 1 b Interaction in medium Pair production γz e + e Z (K N ) Pair production γe e + e e (K e ) Compton scattering γe γe (σ incoherent ) Rayleigh scattering (σ coherent ) Photonuclear absorption (σ nuc ) Atomic photoeffect (σ p.e. ) Cross section (barns/atom) 10 mb 1 Mb 1 kb 1 b σ p.e. σ coherent σ incoh σ nuc κ N κ e σ incoh (b) Lead (Z = 82) experimental σ tot σ nuc 10 mb 10 ev 1 kev 1 MeV 1 GeV 100 GeV Photon Energy κ N κ e

18 Scaling of Material Properties Radiation length X 0 - the material thickness for a certain rate of EM: e ± : de loss dx E X 0 Critical Energy E c : cascade stops Losses: Ionization = Radiation B.Rossi: de ioniz dx Ec E X 0 E c (710) MeV Z +1.24(0.92) solids(gasses) γ: λ e + e 9 7 X 0 Derived from EM calculations: 716 g cm 2 A X 0 Z (Z +1) ln(287/ Z ) E c (MeV) MeV Z Solids Gases 710 MeV Z H He Li Be B CNONe Fe Sn Z

19 Electromagnetic Showers Photons and light charged particles (e ± ) interact with matter: electrons radiate e ± e ± γ photons convert γ e + e A cascade develops till the energy of the particles go below a certain limit. The charged particles of the cascade (e ± ) leave detectable signals.

20 Electromagnetic Shower: longitudinal development Scaling variables: t = x X 0 y = E E c Simple model A simple example of a cascade: 2 at t = 1. E(t) = E 0 t 2 t max = ln E 0 E c /ln 2 t max ln( E 0 E c ) Detectable signal: L charged E 0 /E c Simulation: EGS4, GEANT (1/E 0 )de/dt Energy Photons 1/6.8 Electrons 30 GeV electron incident on iron t = depth in radiation lengths { 0.5 e 100 t max ln(y) γ t(> 95%) t max +0.08Z Fluctuations: mid of cascade σn N t calor t(> 95%) Number crossing plane

21 Electromagnetic Shower: transverse size Molière radius: R M = X 0 21MeV E c R < 2 R M contains 95% of the shower

22 Properties of Materials Density X 0 X 0 λ I Molière E crit Refr. Material g/cm 3 g/cm 2 cm g/cm 2 R M cm MeV index W Pb Cu Al C Plastic H

23 Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

24 Generic Calorimeter A matrix of separate elements: Y Z E = i k k Typically k = 3, 5 E i = α i A i x y = f (.., x i y i, E i,..) X 0 direction E i X 0 Interaction point Measured: A i - measured amplitudes α i - calibration factors (slow variation) x i y i - module coordinates X Important parameters Energy resolution σe E Linearity Coordinate resolution σx Time resolution Stability Specific requirements: radiation hardness. mag. field Cost

25 Generic Calorimeter Shower Cherenkov light Light collection PMT Scint. light APD Amplifier Ionization ADC 10-17bits Electrical signal Current collection DAQ Important procedures Calibration: A i - measured E i = α i A i. α i have to be measured using particles of known energies. Monitoring of the calibration factors α i using detector response to a simple excitation (ex: light from a stable source).

26 Homogeneous and Sampling Calorimeters Consider: EM shower in plastic scintillator Needed length 15 X 0 = 600 cm - not practical! Homogeneous calorimeters (EM) Heavy active material, no passive absorber Best energy resolution Higher cost Sampling calorimeters Heavy material absorber and the active material are interleaved. Features: Compact Relatively cheap Sampling fluctuations impact on σe E

27 Resolutions Energy resolution σe E = α β E γ E α - constant term (calibration) β - stochastic term (signal/shower fluctuations) γ - noise Spatial resolution σx = α 1 β 1 E

28 Energy resolution Fluctuations of the track length (EM): σe E E Fluctuations of the track length (HD): σe E 0.5 E, or 0.2 E with compensation Statistics of the observed signal (EM): σe E > 0.01 E Sampling fluctuations (EM): σe E thickness 0.1 t in X 0 (B.Rossi), for lead absorber (t > 0.2) E Ec t, where t is the layer E Noise, pedestal fluctuations σe E < 0.01 E Calibration drifts σe E 0.01 for a large detector Other...

29 Spacial resolution Module lateral size < shower size Calculating the shower centroid EM: σx > 0.05 R M HD: σx > 1 2cm

30 Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

31 Light Collecting Homogeneous EM Calorimeters Heavy transparent materials (low X 0 ) are preferable compact, larger signal Heavy crystal scintillators: NaI, CsI, BGO, PbW etc: high light yield good resolution, expensive Heavy crystal Cherenkov detectors: PbF, etc: compact, radiation hard Lead glass (SiO PbO) Cherenkov detectors: medium performance, affordable Glass / Crystal Light collection 20-50% Optical coupling PMT /photodiod I(t) τ(90%) Time resolution: Scintillation time Light bouncing Photodetector Typically: τ(90%) 100 ns for Cherenkov detectors

32 Light Collecting Sampling EM Calorimeters Heavy absorber (Pb,Cu,W...) and a scintillator (plastic) or Cherenkov radiator (quartz fibers...). Problem: how to collect the light? The most popular solutions for this moment: SPACAL (Pb, sc. fibers). The fibers can be bundled to the PM. Very good resolution. Difficult to manufacture. Sandwich with WLS fibers crossing through ( shashlik ). The fibers are bundled to the PM. Good resolution. Easy to build. Pb Sc Pb Sc Pb Sc Pb Sc Pb Sc WLS fibers PMT Time resolution: Scintillation time Photodetector time Typically τ(90%) 50 ns

33 Light Detectors Photomultiplier Tubes (PMT) A vacuum vessel with a photocathode and a set of electrodes (dynodes) for electron multimplication. Very high gain Very low electronic noise Size: diameter 2-40 cm Slow drift of the gain Sensitive to the magnetic field Relatively low QE 20% Radiation hard Avalanche Photodiods (APD) A silicon diod in avalanche mode and an electronic amplifier Gain High electronic noise Size: 1 2 cm 2 Very sensitve to the bias voltage Not sensitive to the magnetic field High QE 75% at 430 nm Temperature sensitive -2%/K Radiation hardness may be a problem

34 Crystals in big experiments BaBar CsI(Tl) L3 BGO CMS PbWO

35 EM calorimeters with optical readout Density X 0 R M λ I Refr. τ Peak Light Material g/cm 3 cm cm cm index ns λ nm yield Crystals NaI(Tl) %/E 1/4 CsI %/E 1/2 CsI(Tl) %/E 1/2 BGO %/E 1/2 PbWO /39% %/E 1/2 15/60% /01% LSO %/E 1/2 PbF Cher Cher %/E 1/2 Lead glass TF Cher Cher %/E 1/2 SF Cher Cher %/E 1/2 SF Cher Cher %/E 1/2 Sampling: lead/scintillator SPACAL %/E 1/2 Shashlik %/E 1/2 - hygroscopic Np.e. GeV rad σe E

36 Crystal Ball (SLAC, DESY) 600 NaI crystals γ detection Charmonia spectra QCD tune!

37 KTeV (FNAL) 3256 CsI crystals π γγ detection σe/e 2.0% E + 0.5%

38 Introduction Physics of Showers Calorimetersand afront-end circulatingelectronics radioactive source Procedures (a neutron-activated Summary uorocarbon Appendix uid) produ photon peak in each crystal. Signals from data ( 0 s, s, radiative, and non-rad and + ; events) can provide additional calibration points. Source and Bha are updated weekly to track the small changes in light yield with integrated radia BaBar (SLAC) pulser runs are carried out daily to monitor relative changes at the <0.3% level. The calorimeter has achieved an electronics noise energy (ENE) of 220keV incoherent) measured with the source system (in the absence of colliding beams) af processing. During regular data taking, this digital ltering is not applied and t 450 kev owing to the short shaping time consequently, only channels with >1 M used in the reconstruction of calorimeter energy deposits. The eciency of the cal 96% for the detection of photons with energies above 20 MeV CsI(Tl) crystals The energy resolution can be measured directly with the radioactive source at with electrons from Bhabha scattering at high energies, σe/e 2.3%/E 1/4 yielding resolutions of (E at 6.13 MeV and (E)=E = 1:9 0:07% at 7.5 GeV, respectively % The energy res be inferred from the observed mass resolutions for the 0 and, which are measu 7 MeV and 16 MeV, respectively. (E) / E σ π 0 γγ η γγ Bhabhas χ c J/ψ γ radioakt. Source MonteCarlo /4 σ(e)/e = σ 1 /E σ 2 σ 1 = (2.32 ± 0.03 ± 0.3)% σ 2 = (1.85 ± 0.07 ± 0.1)% / GeV E γ : The BABAR Detector. 1. Silicon Vertex Tracker (SVT), 2. Figure Drift8: Chamber The energy (DCH), resolution as a function of energy, as determined from the le Identication Subsystem (DIRC{Detector of Internally Reected of 0 and Cherenkov decayslight, to two4. photons of equal energy, and the resolution for Bhabh agnetic Calorimeter (EMC), 5. Magnet, 6. Instrumented Fluxshaded Return band (IFR). is the best t to the 0,, and Bhabha data. Also shown is the ene

39 SpaCal (CERN, Frascatti) scintillating fibers / lead matrix Fibers/lead 50% / 50% in volume X = 1.2 cm 5 g/cm 3 CERN - original R&D KLOE (DAFNE) PMTs KLOE σe/e 5.7%/E 1/2 KLOE στ 50/E 1/ ps

40 Front-End Electronics Requirements Resolution 10 3 Dynamic range > 10 2 : needed to measure the shower profile and the coordinates Differential linearity <1% Digitization speed (>10 MHz) Readout speed (>10 MHz) Cost Existing generic solutions Charge integrating ADC Flash ADC Combinations (pipeline ADC)

41 Charge Integrating ADC input gate + Q V C out Integrating ADC Many products on the market Precise: bits Gate must come in time long (> ns) delay for each channel is needed (cables) Slow conversion time > 10 µs not suitable for trigger logic Problems at very high rate: pileup, deadtime Pedestal input Q V V T TDC gate 10us DAQ 100ns

42 Flash ADC V input n digital temperature code Flash ADC encoder 2 ns = 500 MHz * * sampling * * * * * * * * * * n bits memory Cost 10 of the QDC (100 MHz, 12 bits) Huge memory buffers needed Resolution n bits 2 n comparators No dead time No delay cables needed Pileup can be partially resolved Time resolution without extra discr.& TDCs Can be used in trigger logic

43 Calibration The detector has to be calibrated at least once. Test beam Better: in-situ, using an appropriate process: e + e collider: Bhabha scattering e + e e + e, e + e e + e γ LHC: Z e + e (1 Hz at low luminocity) h+h π 0 +X, π 0 γγ RCS (JLab): e p e p χ 2 = n Procedure: for event n: E (n) = i k k (E (n) i k k α i A (n) i α i A (n) i )/σ n System of linear equations N N matrix - nearly diagonal Easy to solve

44 Monitoring Instabilities: All avalanche-type devices tend to drift (PMT, gas amplification...) Optical components may lose transparency Temperature dependence Many other sources of instability... Calibration is typically done once per many days of running signal monitoring in between is needed.

45 Light collecting devices light scattering Lucite plate X Optical fibers Calorimeter optical fibers Stable light source pulsed Stable pulsed light source: Xe flash lamp: 1% stability, >100 ns pulse Laser: 2-5% stability, 1 ns pulse LED: 1-3% stability in thermostate, >30 ns pulse Usually the light source has to be monitored Light distribution Material transparency: not easy to monitor (λ-dependence) Scintillation yield - no monitoring this way Stable light source pulsed

46 Summary Calorimeters are used for: Detecting neutrals Energy and coordinate measurements Trigger Separation of hadrons against e ±, γ and muons The calorimeters are of increasing importance with higher energies. They become the most important/expensive/large detectors in the current big projects (LHC, CLIC etc).

47 Summary (continued) There are various techniques to build calorimeters for different resolution, price, radiation hardness and other requirements. The typical energy resolutions are: EM: from σe E 2% E 0.3% for scintillating crystals to about σe E 10% 0.8% for sampling calorimeters. E HD calorimeters: σe E 30 50% 3% E The coordinate resolutions could be about 1-3 mm for EM calorimeters and mm for HD ones.

48 Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

49 Charge collecting EM Calorimeters Ionization electrical charge collected in electrical field. Sensitive to electro-negative contaminations. Active materials with electron/ion mobility: Solids: semiconductor (Si), no amplification, rad. soft/hard Liquids (no amplification, rad. very hard): cryo Ar (sampling, impurities <ppm), Kr, Xe (impurities <ppb) warm organic liquids (impurities ppb) Gas, sampling: low signals if no gas amplification used. Landau fluctuations. High pressure (20-30 atm), no aplification, rad. hard, but low signals gas wire chambers (with amplification), rad soft Detector with no cascade-type amplification (like happens in wire chambers, PMT etc) have a much more stable calibration. But: low signals amplifiers sensitive to electronic noise.

50 Electrical Signal q E Induced Charge: Ramo-Shockley Theorem A V I(t) = q ( v E) V Q = I(t)dt = q Ionization collection Electrons and ions add to the signal. The velocities of electrons and ions are orders of magnitude different.

51 ÈÈÅ ÆÊË»ÁÆ¾È ÍÒ Úº Å Ø ÖÖ Ò Å Ö ÐÐ Ö Ò Introduction Physics of Showers Calorimeters Front-End Electronics Procedures Summary Appendix Ì Ô Ý ÔÖÓ Ö Ñ Ø ÄÀ ÐÝ Ñ Ò Ò Ò Ø ÖÑ Ó Ø ØÓÖ Ô Ö ÓÖÑ Ò º ÁÒ Ô ÖØ ÙÐ Ö Ø ÌÄ Ë Ð ØÖÓÑ Ò Ø ÐÓÖ Ñ Ø Ö ØÓ Ñ Ø ÐÐ Ò Ò Ö ÕÙ Ö Ñ ÒØ ÓÖ Ò Ö Ý ÔÓ Ø ÓÒ Ò Ø Ñ Ö ÓÐÙØ ÓÒ º ÐÓÖ Ñ Ø Ö ÔÖÓØÓØÝÔ Ò ÔÖÓ ÙØ ÓÒ ÑÓ ÙÐ Ú Ò Ø Ø ÙÒ Ö Ð ØÖÓÒ Ñ Ø ÊÆ ÙÖ Ò Ø Ð Ø Ø Ö Ý Ö º Ê ÙÐØ Ö ÔÖ ÒØ Ò ÓÑÔ Ö ØÓ ÌÄ Ë Ö ÕÙ Ö Ñ ÒØ º Liquid Argon Calorimeters ½º ÁÒØÖÓ ÙØ ÓÒ X 0 = 14 cm - rather long SAMPLING V e = 3 µm/ns at 5 kv/cm e /GeV typically Ô Ö ÝÑÑ ØÖ Ô ÖØ Ð Ö º Widely used: H1 (Pb,Fe), D0 (U), SLD, ATLAS (Pb) Ó Ð ØÖÓÒ Ò Ô ÓØÓÒ º Very stable (1%/year at SLD) ATL-CONF July 2003 Ì ÌÄ Ë ÌÓÖÓ Ð ÄÀ ÔÔ Ö ØÙ˵ ܹ Ô Ö Ñ ÒØ ½ ÔÖ ÒØÐÝ ÙÒ Ö ÓÒ ØÖÙØ ÓÒ Û ÐÐ Ø ÖØ ÓÔ Ö Ø ÓÒ Ò ¾¼¼ Ø Ø ÄÀ ¾ ÔÖÓØÓÒ¹ ÔÖÓØÓÒ ÓÐÐ Ö Ø Êƺ Ì ÑÙÐØ ¹ÔÙÖÔÓ ¹ Ø ØÓÖ Û Ô Ý ÔÖÓ Ö Ñ Ô ÒÒ Ò ÖÓÑ ÔÖ ÓÒ Ñ ÙÖ Ñ ÒØ Ó Ï Ó ÓÒ ØÓÔ Ò ÓØØÓÑ ÕÙ Ö ÔÖÓÔ ÖØ ØÓ À Ó ÓÒ ÓÖ Ù¹ ÁÒ ÑÓ Ø Ø Ð ØÖÓÑ Ò Ø Åµ ÐÓÖ Ñ Ø Ö Û ÐÐ ÔÐ Ý Ý ÖÓÐ Ò Ñ ÙÖ Ò Ò Ö Ý ÔÓ Ø ÓÒ Ò Ø Ñ ¾º Ò Ö Ð Ð ÝÓÙØ Ó Ø ÌÄ Ë Ð ØÖÓ¹ Ñ Ò Ø ÐÓÖ Ñ Ø Ö Ì ÄÀ ÜØÖ Ñ ÓÔ Ö Ø Ò ÓÒ Ø ÓÒ ÑÔÓ Ú Ö ÓÒ ØÖ ÒØ ÓÒ Ø ØÓÖ Ò Ø ÖÑ Ó Ö ¹ Ø ÓÒ ØÓÐ Ö Ò ÖÓÙÒ Ö Ø ÓÒ Ô Ð¹ ØÝ ÒÓ Ò Ð Ò Ö ÔÓÒ Ô Ô Ø Ð ÓÚ¹ Ö Ò Ø Ñ Ø Ð Øݺ Ì Å ÐÓÖ Ñ Ø Ö Ð ¹Ð ÕÙ Ö ÓÒ Ä Öµ ÑÔÐ Ò ÐÓÖ Ñ ¹ Ø Ö Û Ø Ò ÓÖ ÓÒ ÓÑ ØÖÝ Ø Ø Ù Ö¹ ÒØ ÙÐÐ Þ ÑÙØ Ð ÓÚ Ö º ÁØ Ú Ò ÓÒ ÖÖ Ð ½ µ Ò ØÛÓ Ò ¹ Ô ½ ¾µ Ò Ñ ÒØ Ò ÔØ Ò Ø Ö ÓÑÔ ÖØÑ ÒØ ÙÖ ½µº Ì Ñ¹ ÔÐ Ò ½ ÖÓÒص Ñ Ó Ò ÖÖÓÛ ØÖ Ô Ò Ô Ö¹ ÓÖÑ ÔÖ ÔÓ Ø ÓÒ Ñ ÙÖ Ñ ÒØ Ò ¼ Ô Ö Ø ÓÒº Ì ÑÔÐ Ò ¾ Ñ Ð µ ÔØ ØÖÓÑ Ò Ø Ô ÖØ Ð º ÁÒ Ø ÓÒ Ø Ò ÔÖ ¹ ÑÔÐ Ö Ø ØÓÖ ÓÖÖ Ø Ò Ö Ý ÐÓ Ò Ø ÙÔ¹ ØÖ Ñ Ñ Ø Ö Ð ÓÖ ½ º ÁÒ ØÓØ Ð ÐÑÓ Ø ¾¼¼ ¼¼¼ Ö ¹ÓÙØ ÒÒ Ð Ú Ø Ø ØÓÖ Ö ÒÙÐ Ö Øݺ Ä ÕÙ Ö ÓÒ Ò Ó Ò ÓÖ Ø ÒØÖ Ò Ð Ò Ö Ú ÓÖ Ö ÔÓÒ Ø Ð ØÝ Ò Ö Ø ÓÒ ØÓÐ Ö Ò º ÓÖ Ó ÓÒ ØÖÙØ ÓÒ Ø ÖÖ Ð Ô ÖØ Ú Ò ¾ ÑÓ ÙÐ Ò Ò ¹ Ô Û Ð Ñ Ó ÑÓ ÙÐ º Ì ÓÒ¹ ØÖÙØ ÓÒ Ø Ø Ò ÒØ Ö Ø ÓÒ Ó Ø ÑÓ ÙÐ Ö ÔÖ ÒØÐÝ Û ÐÐ Ú Ò Ò Ö Ø Ð Ò Ô Ö Ø ÓÒØÖ ÙØ ÓÒ Û Ø Ò Ø ÔÙ Ð Ø ÓÒº ATLAS (LHC) Accordion structure 2 mm Pb, 3 mm LAr 2-5 kv on the gaps Amplifiers 100 noise < 5000e High capacitance noise η = 0 4.3X0 ϕ=0.0245x4 36.8mmx4 =147.3mm 1500 mm 470 mm ϕ 1.7X 0 16X mm/8 = 4.69 mm η = η 2X0 Towers in Sampling 3 ϕ η = η = ϕ = Strip towers in Sampling 1 Trigger Tower η = 0.1 Trigger Tower Square towers in Sampling 2 ϕ =

52 Liquid Krypton Calorimeters X 0 = 4.5 cm - can be homogenous Signal 2 of LAr Expensive Experiment NA-48: 4 m 3, homogeneous, thickness 27 X 0, 13k channels. Resolution Energy (GeV) σe E = 0.4% 3.2% E 0.1 GeV E

53 Monitoring: charge collecting devices Media purity (LAr...) - general control Electrical pulse to monitor each electronic channel electrodes V + test pulse Very good stability ( 1%/year) reached in LAr detectors

54 Outline 1 Introduction 2 Physics of Showers 3 Calorimeters Generic calorimeter Light collecting calorimeters 4 Front-End Electronics 5 Procedures 6 Summary 7 Appendix Charge collecting calorimeters Hadron calorimeters

55 Hadronic Shower High energy nuclear interaction on a nucleus: h + A i h±,0 i + i π0 i, and π0 γγ. π 0 yield N π 0/N tot 0.1 ln E signal strong fluctuations depending on the first interaction a sizable amount of energy goes to nuclear excitation important parameter: response ratio e/h e/h 1 - non-linear with energy, poor resolution e/h = 1 - compensated calorimeter Scale: interaction length λ I 35 g/cm 2 A 1/3 Shower max: x/λ I = t max 0.2 ln(e/1gev ) + 0.7

56 Hadronic Shower % 10 Depth in Iron (cm) % / Bock param. / CDHS data / CCFR data Depth in Iron (λ I ) Single Hadron Energy (GeV) 3

57 Hadron Calorimeters SPACAL σe E 30% E 3% L Ar Tile σe E 52% E 3% σe E 60% E 2%