Calorimeter Calibration and Jet Energy Scale

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Jean-Francois Arguin November 28 th , 2005 Physics 252B, UC Davis Calorimeter Calibration and Jet Energy Scale

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Outline Quick rest of calorimetry Calibration before the trial begins: test pillar Calibration when the examination is running: Hardware alignment Collider information Measuring planes at high-vitality colliders Example of a physical science estimation: beat quark mass

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Basics of Calorimetry Incident molecule makes a shower inside material Shower can be either electromagnetic or hadronic Energy is stored in material through ionization/excitation

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Basics of Calorimetry II Basic rule of calorimetry: saved vitality is corresponding to occurrence vitality Calorimeter adjustment make an interpretation of indicator reaction to episode vitality Great component of showers for identifier utilize: length is relative to logE

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Electromagnetic showers Created by occurrence photon and electron electrons emanate bremstrahlung photons experience match generation Length of shower communicated in term of X 0 X 0 relies on upon material 95% control requires regularly around 20X 0

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Created by occurrence charged pion, kaon, proton, and so forth Typical organization: half EM (e.g. ) 25% Visible non-EM vitality 25% undetectable vitality (atomic separations) Requires longer regulation (communicated in λ) Hadronic showers

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Calorimeter indicators Detector equipment must: Favor shower advancement Collect kept vitality Can do both in the meantime (e.g. BaBar/Belle precious stone calorimeters) Or have calorimeters with substituting inactive and delicate material Example of electron give lead safeguard:

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Sampling calorimetry (Ex.: CDF) Scintillators (touchy material) transmit lights with section of ionizing particles Collect light kept in delicate material utilizing wavelength shifter (WLS) WLS → photomultipliers that change over light into electric flag

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CDF Calorimeters Segmentation Calorimeter is portioned into towers that are perused out autonomously Lead (press) blended with scintillators for EM (HAD) calorimeters Each focal tower covers Each tower has an EM calorimeter took after by a HAD calorimeter

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CDF Calorimeters Three districts: focal, divider and attachment Use "projective" geometry Designed to gauge electrons, photons, quarks, gluons, hadrons, neutrinos Note: outline of calorimeter performed with a reproduction of the most critical procedures you plan to quantify (ex.: Higgs at LHC)

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Construction Go on and manufactured the thing after it is composed! Numerous foundations on the planet partake

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First alignment: test pillar Take one calorimeter "wedge", send light emission with known vitality Obtain correspondence identifier reaction → vitality in GeV A couple towers just submitted to test shaft Set total scale for all towers Relative scale for different towers acquired later Wedge inspiring prepared to get bar:

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How does the test bar works (Ex.: plug calorimeter) Why Muons? Performed at Fermilab meson bar offices Beams attributes: Various sorts for EM and HAD showers: electrons , pions , muons Various vitality: 5-120 GeV (electrons), 5-220 GeV (pions) Beams can be sullied → inclination the alignment constants E.g. utilize Cherenkov identifier before calorimeter to recognize proton tainting in pion pillar

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Calorimeter reaction linearity Extract adjustment consistent for some vitality point Can test linearity of calorimeter Can include "fake" material before calorimeter to reproduce tracker+magnet material Send pions and electrons to hadronic calorimeter Why sending electrons in hadron calorimeter?

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Performance decided from test shaft From RMS of tower reaction to same pillar vitality → measure calorimeter determination Can test tower transverse consistency (impacts determination) Stochastic term determination: EM: HAD:

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Final locator gathering: getting prepared for material science!

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The Tevatron Proton-antiproton crashes at Most fiery collider on the planet Collisions each 0.4 μ s Circumference of 6.3 km

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The CDF Detector CDF II: broadly useful solenoidal locator 7 layers of silicon following Vertexing, B-labeling COT: float chamber scope Resolution: Muon chambers Proportional chamber scattered with safeguard Provide muon ID up-to Calorimeters Central, divider, plug calorimeter

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Calibration when the finder is introduced Only a couple towers saw test shaft, how to align the entire thing?? Test bar sets the supreme scale as a capacity vitality Two arrangements: Hardware alignments Physics adjustment (utilizing collider information) These adjustments need to: Cross-check total scale (e.g. test bar not 100% reasonable) Track locator reaction through time Expected corruption of scintillator and PMT touchy to temperature Uniform reaction through all towers

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Hardware alignment Can utilize radioactive sources that have extremely all around characterized rot vitality Cobalt 60 (2.8 MeV) Cesium 137 (1.2 MeV) Source adjustment can be performed between colliders run Sources are portable and can uncover one tower at once Check consistency over all towers and after some time Sources are delicate to both scintillator and PMT reactions

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Laser adjustments The lasers are associated straightforwardly to PMTs Skip scintillator/WLS steps Used to uniformize PMTs reaction over towers and time

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Physics adjustments Use genuine collider information For adjustment, you need to have some "known" and some "obscure" (the calorimeter reaction) Examples of "known" data: Mass of an outstanding particles Ex.: Z →ee (Z mass measured at LEP) Energy kept by muons over a given length Muon test Energy measured in tracker (accepting tracker in aligned) Redundant to vitality measured in calorimeter for electrons

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Example: Z boson mass Z mass pinnacle: Z mass measured with extraordinary precision at LEP utilizing pillar vitality Background is little for Z →ee Sample is moderately little, however adequate

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Example: E/p of electrons Used for relative scale over towers Cannot be utilized as a part of forward locale (no tracker) In fitting: depend on sourcing and lasers

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Example: muons for HAD calorimeters Muon align identifier reaction to ionizing vitality Use muon from J/ψ for recognizable proof (mass not utilized like Z boson) Again, not utilized for PHA (depend on sourcing, laser)

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Physics with photons/electrons Search for new material science: Z " applicant: Calorimeter alignment by all account not the only issue Electron/photon physical science likewise depend on following Removal of foundation E.g. expel pion foundation by considering shower shape Precision estimation: W mass:

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What are planes? Why not utilizing tracker (has better determination)? Planes are a collimated gathering of particles that outcome from the fracture of quarks and gluons They are measured as groups in the calorimeter force of bunch of towers is connected with the force of the first quark and lepton

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Phenomenology of planes Quark/gluon delivered from ppbar communication Fragmentation into hadrons Jets grouping calculation: Adds towers inside cone Fraction of vitality is out-of-cone Underlying occasion contributes

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Jet versus calorimeter vitality scale Jets are confused procedures Previous calorimeter adjustments are not adequate to get aligned stream vitality More work should be finished!! Fly vitality scale is essential for some imperative estimations: Top quark mass (used to compel Higgs boson) Jet cross-segments (correlation with QCD expectations) Measurements frequently performed by contrasting genuine information with recreations Need with get both material science and finder reenactment right

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Relative vitality scale Relative vitality scale: Use QCD dijet occasions Should have square with transverse force Jet vitality estimation rely on upon area in identifier True even after every past adjustment! Why? Planes are wide Some districts of CDF calorimeter are not instrumented

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Absolute vitality scale Solution: Get the normal vitality scale Simulate a "normal" particles setup inside fly Use test pillar data to get adjustment figure for single particles Response to single pion non-direct (in test shaft) However, planes are distinguished as one single articles For a 50 GeV stream: alignment is not the same whether: One 50 GeV pion 10 times 5 GeV pions

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Out-of-cone vitality Cone of altered range used to recognize planes Need to remedy for portion of vitality out-of-cone (commonly 15%) This is for the most part material science related How well is the physical science generator speaking to discontinuity?

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Underlying occasion vitality Proton/antiproton remainders sprinkle vitality in calorimeter Spoils stream vitality estimation Depends on the quantity of ppbar communication per occasion Extracted from "least predisposition" occasions Small impact: ~0.4 GeV per fly

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Final fly vitality scale instability Estimate of fly vitality scale vulnerability is vital to gauge precise instabilities of estimations Dominated by out-of-cone (low-p T ) and outright vitality scale (high-p T ) Ranges from 10% to 3% vitality instabilities

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Example material science estimation: best quark mass Top created in sets at Tevatron Top rots to W boson and b-quark 100% of time in SM Typical occasion determinations: Well-distinguished electron(s) or muon(s) Large missing ET Several remade planes recognized in calorimeters Note: 4 flies in definite state!

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Identification of b-quark planes Complicated last state: Which planes originate from which parton? Can distinguish b-quark planes utilizing one trademark: Long b-quark lifetime Note: bunches of semileptonc B-hadrons rot (including neutrino) Require uncommon b-planes adjustment

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Top mass recreation Event-by-occasion kinematic fitter (expect occasion is ttbar) Attempts all stream p