An Introduction to Particle Detectors

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A bubble chamber is a vessel flled with a superheated transparent liquid (most oten liquid

hydrogen) used to detect electrically charged particles moving through it. It was invented in 195

!y "onald A. #laser$%1& or which he was awarded the 19' o!el *ri+e in *hysics.%&,upposedly$

#laser was inspired !y the !u!!les in a glass o !eer- however$ in a ' tal$ he reuted this

story$ although saying that while !eer was not the inspiration or the !u!!le cham!er$ he did

e/periments using !eer to fll early prototypes.%0&

loud cham!ers wor on the same principles as !u!!le

cham!ers$ !ut are !ased on supersaturated vapor rather

than superheated liquid. 2hile !u!!le cham!ers weree/tensively used in the past$ they have now mostly !een

supplanted !y wire cham!ers and spar cham!ers.

3istorically$ nota!le !u!!le cham!ers include the 4ig

uropean 4u!!le ham!er (44) and #argamelle.

A !u!!le cham!er

6he !u!!le cham!er is similar to a cloud cham!er$ !ot

in application and in !asic principle. It is normally made

!y flling a large cylinder with a liquid heated to 7ust

!elow its !oiling point. As particles enter the cham!er$

a piston suddenly decreases its pressure$ and the liquid

enters into a superheated$ metasta!le phase. harged

particles create an ioni+ation trac$ around which the

liquid vapori+es$ orming microscopic !u!!les. 4u!!le

density around a trac is proportional to a particle8s

energy loss.

4u!!les grow in si+e as the cham!er e/pands$ until

they are large enough to !e seen or photographed.

,everal cameras are mounted around it$ allowing a

threedimensional image o an event to !e captured.

4u!!le cham!ers with resolutions down to a

ew :m have !een operated.

https://en.wikipedia.org/wiki/Superheatinghttps://en.wikipedia.org/wiki/Transparency_(optics)https://en.wikipedia.org/wiki/Liquidhttps://en.wikipedia.org/wiki/Liquid_hydrogenhttps://en.wikipedia.org/wiki/Liquid_hydrogenhttps://en.wikipedia.org/wiki/Electric_chargehttps://en.wikipedia.org/wiki/Donald_A._Glaserhttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-1https://en.wikipedia.org/wiki/Nobel_Prize_in_Physicshttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-2https://en.wikipedia.org/wiki/Beerhttps://en.wikipedia.org/wiki/Prototypehttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-3https://en.wikipedia.org/wiki/Cloud_chamberhttps://en.wikipedia.org/wiki/Supersaturationhttps://en.wikipedia.org/wiki/Wire_chamberhttps://en.wikipedia.org/wiki/Spark_chamberhttps://en.wikipedia.org/wiki/Big_European_Bubble_Chamberhttps://en.wikipedia.org/wiki/Big_European_Bubble_Chamberhttps://en.wikipedia.org/wiki/Gargamellehttps://en.wikipedia.org/wiki/Cloud_chamberhttps://en.wikipedia.org/wiki/Boiling_pointhttps://en.wikipedia.org/wiki/Pistonhttps://en.wikipedia.org/wiki/Metastablehttps://en.wikipedia.org/wiki/Liquid_bubblehttps://en.wikipedia.org/wiki/Micrometershttps://en.wikipedia.org/wiki/File:Bubble-chamber.svghttps://en.wikipedia.org/wiki/Superheatinghttps://en.wikipedia.org/wiki/Transparency_(optics)https://en.wikipedia.org/wiki/Liquidhttps://en.wikipedia.org/wiki/Liquid_hydrogenhttps://en.wikipedia.org/wiki/Liquid_hydrogenhttps://en.wikipedia.org/wiki/Electric_chargehttps://en.wikipedia.org/wiki/Donald_A._Glaserhttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-1https://en.wikipedia.org/wiki/Nobel_Prize_in_Physicshttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-2https://en.wikipedia.org/wiki/Beerhttps://en.wikipedia.org/wiki/Prototypehttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-3https://en.wikipedia.org/wiki/Cloud_chamberhttps://en.wikipedia.org/wiki/Supersaturationhttps://en.wikipedia.org/wiki/Wire_chamberhttps://en.wikipedia.org/wiki/Spark_chamberhttps://en.wikipedia.org/wiki/Big_European_Bubble_Chamberhttps://en.wikipedia.org/wiki/Big_European_Bubble_Chamberhttps://en.wikipedia.org/wiki/Big_European_Bubble_Chamberhttps://en.wikipedia.org/wiki/Gargamellehttps://en.wikipedia.org/wiki/Cloud_chamberhttps://en.wikipedia.org/wiki/Boiling_pointhttps://en.wikipedia.org/wiki/Pistonhttps://en.wikipedia.org/wiki/Metastablehttps://en.wikipedia.org/wiki/Liquid_bubblehttps://en.wikipedia.org/wiki/Micrometers


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6he entire cham!er is su!7ect to a constant magnetic feld$ which causes charged particles to

travel in helical paths whose radius is determined !y their chargetomass ratios and their

velocities. ,ince the magnitude o the charge o all nown charged$ longlived su!atomic particles

is the same as that o an electron$ their radius o curvature must !e proportional to

their momentum. 6hus$ !y measuring their radius o curvature$ their momentum can !e

determined.

ota!le discoveries made !y !u!!le cham!er include the discovery o wea neutral

currents at #argamelle in 19;0$%0 (at the ?A1 and ?A e/periments). @ecently$!u!!le cham!ers have !een used in research on 2I*s$ at B?** and *IA,,B.%5&%'&

,ome o the pictures taen !y the !u!!le cham!er

,C@B6@B-

A synchrotron is a particular type of cyclic particle accelerator , descended from the cyclotron, in which the guiding

magnetic field (bending the particles into a closed path) is time-dependent, being synchronized to a particle beam of

increasing kinetic energy (see image[1]). he synchrotron is one of the first accelerator concepts to enable the

construction of large-scale facilities, since bending, beam focusing and acceleration can be separated into different

components. he most powerful modern particle accelerators use !ersions of the synchrotron design. he largest

synchrotron-type accelerator is the "# kilometre (1# mi) circumference $arge %adron &ollider ($%&) near 'ene!a,

witerland, built in "**+ by the uropean rganiation for uclear /esearch (&/).

https://en.wikipedia.org/wiki/Helixhttps://en.wikipedia.org/wiki/Charge-to-mass_ratiohttps://en.wikipedia.org/wiki/Electronhttps://en.wikipedia.org/wiki/Momentumhttps://en.wikipedia.org/wiki/Neutral_currenthttps://en.wikipedia.org/wiki/Neutral_currenthttps://en.wikipedia.org/wiki/Gargamellehttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-4https://en.wikipedia.org/wiki/Electroweak_theoryhttps://en.wikipedia.org/wiki/W_and_Z_bosonshttps://en.wikipedia.org/wiki/UA1_experimenthttps://en.wikipedia.org/wiki/UA2_experimenthttps://en.wikipedia.org/wiki/Weakly_interacting_massive_particleshttps://en.wikipedia.org/wiki/COUPPhttps://en.wikipedia.org/wiki/PICASSOhttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-5https://en.wikipedia.org/wiki/Bubble_chamber#cite_note-6https://en.wikipedia.org/wiki/Particle_acceleratorhttps://en.wikipedia.org/wiki/Particle_acceleratorhttps://en.wikipedia.org/wiki/Particle_acceleratorhttps://en.wikipedia.org/wiki/Cyclotronhttps://en.wikipedia.org/wiki/Particle_beamhttps://en.wikipedia.org/wiki/Kinetic_energyhttps://en.wikipedia.org/wiki/Synchrotron#cite_note-1https://en.wikipedia.org/wiki/Large_Hadron_Colliderhttps://en.wikipedia.org/wiki/Large_Hadron_Colliderhttps://en.wikipedia.org/wiki/European_Organization_for_Nuclear_Researchhttps://en.wikipedia.org/wiki/European_Organization_for_Nuclear_Researchhttps://en.wikipedia.org/wiki/Helixhttps://en.wikipedia.org/wiki/Charge-to-mass_ratiohttps://en.wikipedia.org/wiki/Electronhttps://en.wikipedia.org/wiki/Momentumhttps://en.wikipedia.org/wiki/Neutral_currenthttps://en.wikipedia.org/wiki/Neutral_currenthttps://en.wikipedia.org/wiki/Gargamellehttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-4https://en.wikipedia.org/wiki/Electroweak_theoryhttps://en.wikipedia.org/wiki/W_and_Z_bosonshttps://en.wikipedia.org/wiki/UA1_experimenthttps://en.wikipedia.org/wiki/UA2_experimenthttps://en.wikipedia.org/wiki/Weakly_interacting_massive_particleshttps://en.wikipedia.org/wiki/COUPPhttps://en.wikipedia.org/wiki/PICASSOhttps://en.wikipedia.org/wiki/Bubble_chamber#cite_note-5https://en.wikipedia.org/wiki/Bubble_chamber#cite_note-6https://en.wikipedia.org/wiki/Particle_acceleratorhttps://en.wikipedia.org/wiki/Cyclotronhttps://en.wikipedia.org/wiki/Particle_beamhttps://en.wikipedia.org/wiki/Kinetic_energyhttps://en.wikipedia.org/wiki/Synchrotron#cite_note-1https://en.wikipedia.org/wiki/Large_Hadron_Colliderhttps://en.wikipedia.org/wiki/European_Organization_for_Nuclear_Research


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CMS by layers

0or full technical details about the & detector, please see the echnical 2esign /eport.

The interaction point

his is the point in the centre of the detector at which proton-proton collisions occur between the two counter-rotatingbeams of the $%&. At each end of the detector magnets focus the beams into the interaction point. At collision each

beam has a radius of 1# 3m and the crossing angle between the beams is "+4 3rad.

At full design luminosity each of the two $%& beams will contain ",+*+ bunches of 1.1451*11 protons. he inter!al

between crossings is "4 ns, although the number of collisions per second is only 61.7 million due to gaps in the

beam as in8ector magnets are acti!ated and deacti!ated.

At full luminosity each collision will produce an a!erage of "* proton-proton interactions. he collisions occur at a

centre of mass energy of + e9. :ut, it is worth noting that for studies of physics at the electroweak scale, the

scattering e!ents are initiated by a single ;uark or gluon from each proton, and so the actual energy in!ol!ed in each

collision will be lower as the total centre of mass energy is shared by these ;uarks and gluons (determined by

the parton distribution functions).

he first test which ran in eptember "**+ was e


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Layer 1 – The tracker

omentum of particles is crucial in helping us to build up a picture of e!ents at the heart of the collision. ne method

to calculate the momentum of a particle is to track its path through a magnetic field? the more cur!ed the path, the

less momentum the particle had. he & tracker records the paths taken by charged particles by finding their

positions at a number of key points.

he tracker can reconstruct the paths of high-energy muons, electrons and hadrons (particles made up of ;uarks) as

well as see tracks coming from the decay of !ery short-li!ed particles such as beauty or @b ;uarks that will be used

to study the differences between matter and antimatter.

he tracker needs to record particle paths accurately yet be lightweight so as to disturb the particle as little as

possible. Bt does this by taking position measurements so accurate that tracks can be reliably reconstructed using

8ust a few measurement points. ach measurement is accurate to 1* Cm, a fraction of the width of a human hair. Bt is

also the inner most layer of the detector and so recei!es the highest !olume of particlesD the construction materials

were therefore carefully chosen to resist radiation. [#]

he & tracker is made entirely of siliconD the pi


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Layer 2 – The Electromagnetic Calorimeter

he lectromagnetic &alorimeter (&A$) is designed to measure with high accuracy the energies

of electrons and photons.

he &A$ is constructed from crystals of lead tungstate, Ib>E. his is an e


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he brass used in the endcaps of the %&A$ used to be /ussian artillery shells. [=]

Layer 4 – The magnet

he & magnet is the central de!ice around which the e


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multiplying the speed of an electron in the tube by the time taken) 2s gi!e two coordinates for the muonJs position.

ach 2 chamber, on a!erage "m < ".4m in sie, consists of 1" aluminium layers, arranged in three groups of four,

each with up to 7* tubesD the middle group measures the coordinate along the direction parallel to the beam and the

two outside groups measure the perpendicular coordinate.

&athode strip chambers (&&) are used in the endcap disks where the magnetic field is une!en and particle rates

are high. &&s consist of arrays of positi!ely charged @anode wires crossed with negati!ely charged copper

@cathode strips within a gas !olume. >hen muons pass through, they knock electrons off the gas atoms, which flock

to the anode wires creating an a!alanche of electrons. Iositi!e ions mo!e away from the wire and towards the

copper cathode, also inducing a charge pulse in the strips, at right angles to the wire direction. :ecause the strips

and the wires are perpendicular, we get two position coordinates for each passing particle. Bn addition to pro!iding

precise space and time information, the closely spaced wires make the &&s fast detectors suitable for triggering.

ach && module contains si< layers making it able to accurately identify muons and match their tracks to those in

the tracker.

/esisti!e plate chambers (/I&) are fast gaseous detectors that pro!ide a muon trigger system parallel with those of

the 2s and &&s. /I&s consist of two parallel plates, a positi!ely charged anode and a negati!ely charged

cathode, both made of a !ery high resisti!ity plastic material and separated by a gas !olume. >hen a muon passesthrough the chamber, electrons are knocked out of gas atoms. hese electrons in turn hit other atoms causing an

a!alanche of electrons. he electrodes are transparent to the signal (the electrons), which are instead picked up by

eikipedia, the free encyclopedia

This article is about the physics concept. For the novel, see The Elementary Particles.

lementary particles included in the tandard odel

Bn particle physics, an elementary particle or fundamental particle is a particle whose substructure is unknown,thus it is unknown whether it is composed of other particles. [1] Rnown elementary particles include thefundamental fermions (;uarks,leptons, anti;uarks, and antileptons), which generally are Qmatter particlesQ andQantimatter particlesQ, as well as the fundamental bosons (gauge bosons and %iggs boson), which generally areQforce particlesQ that mediate interactions among fermions.[1] A particle containing two or more elementary particles isa composite particle.

https://en.wikipedia.org/w/index.php?title=Cathode_strip_chambers&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Resistive_plate_chambers&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Resistive_plate_chambers&action=edit&redlink=1https://en.wikipedia.org/wiki/The_Elementary_Particleshttps://en.wikipedia.org/wiki/The_Elementary_Particleshttps://en.wikipedia.org/wiki/Standard_Modelhttps://en.wikipedia.org/wiki/Particle_physicshttps://en.wikipedia.org/wiki/Particlehttps://en.wikipedia.org/wiki/Particlehttps://en.wikipedia.org/wiki/Particlehttps://en.wikipedia.org/wiki/Substructurehttps://en.wikipedia.org/wiki/Substructurehttps://en.wikipedia.org/wiki/Substructurehttps://en.wikipedia.org/wiki/Elementary_particle#cite_note-PFIp1-3-1https://en.wikipedia.org/wiki/Fermionhttps://en.wikipedia.org/wiki/Quarkhttps://en.wikipedia.org/wiki/Leptonhttps://en.wikipedia.org/wiki/Antiquarkhttps://en.wikipedia.org/wiki/Antiquarkhttps://en.wikipedia.org/wiki/Antileptonhttps://en.wikipedia.org/wiki/Antimatterhttps://en.wikipedia.org/wiki/Bosonhttps://en.wikipedia.org/wiki/Gauge_bosonhttps://en.wikipedia.org/wiki/Higgs_bosonhttps://en.wikipedia.org/wiki/Fundamental_interactionshttps://en.wikipedia.org/wiki/Fundamental_interactionshttps://en.wikipedia.org/wiki/Fundamental_interactionshttps://en.wikipedia.org/wiki/Elementary_particle#cite_note-PFIp1-3-1https://en.wikipedia.org/wiki/List_of_particleshttps://en.wikipedia.org/wiki/List_of_particleshttps://en.wikipedia.org/wiki/File:Standard_Model_of_Elementary_Particles.svghttps://en.wikipedia.org/w/index.php?title=Cathode_strip_chambers&action=edit&redlink=1https://en.wikipedia.org/w/index.php?title=Resistive_plate_chambers&action=edit&redlink=1https://en.wikipedia.org/wiki/The_Elementary_Particleshttps://en.wikipedia.org/wiki/Standard_Modelhttps://en.wikipedia.org/wiki/Particle_physicshttps://en.wikipedia.org/wiki/Particlehttps://en.wikipedia.org/wiki/Substructurehttps://en.wikipedia.org/wiki/Elementary_particle#cite_note-PFIp1-3-1https://en.wikipedia.org/wiki/Fermionhttps://en.wikipedia.org/wiki/Quarkhttps://en.wikipedia.org/wiki/Leptonhttps://en.wikipedia.org/wiki/Antiquarkhttps://en.wikipedia.org/wiki/Antileptonhttps://en.wikipedia.org/wiki/Antimatterhttps://en.wikipedia.org/wiki/Bosonhttps://en.wikipedia.org/wiki/Gauge_bosonhttps://en.wikipedia.org/wiki/Higgs_bosonhttps://en.wikipedia.org/wiki/Fundamental_interactionshttps://en.wikipedia.org/wiki/Elementary_particle#cite_note-PFIp1-3-1https://en.wikipedia.org/wiki/List_of_particles


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o #." e


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• 0orce particles (gauge bosons)D• photon

• gluon (numbering eight)[1]

• !V , !W , and "* bosons

• gra!iton (hypothetical)[1]

• calar boson

•

%iggs boson

A particleHs mass is ;uantified in units of energy !ersus the electronHs (electron!olts). hrough con!ersion of energyinto mass, any particle can be produced through collision of other particles at high energy,[1][11] although the outputparticle might not contain the input particles, for instance matter creation from colliding photons. $ikewise, thecomposite fermions protons were collided at nearly light speed to produce a %iggs boson, which elementary boson ifar more massi!e.[11] he most massi!e elementary particle, the top ;uark, rapidly decays, but apparently does notcontain, lighter particles.

>hen probed at energies a!ailable in e


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'raphic representation of the standard model. pin, charge, mass and participation in different force interactions are shown. &lic

on the image to see the full description

he tandard odel of particle physics contains 1" fla!ors of elementary fermions, plus theircorresponding antiparticles, as well as elementary bosons that mediate the forces and the %iggs boson, which was

reported on Ouly E, "*1", as ha!ing been likely detected by the two main e


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up quark u charm quark c top quark t

down quark d strange quark s bottom quark b

#ntiparticles[edit]Main article: #ntimatter

here are also 1" fundamental fermionic antiparticles that correspond to these 1" particles. 0or e


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proton should be uniform and the electron should scatter elastically. $ow-energy electrons do scatter in this way, butabo!e a particular energy, the protons deflect some electrons through large angles. he recoiling electron has muchless energy and a 8et of particles is emitted. his inelastic scattering suggests that the charge in the proton is notuniform but split among smaller charged particlesD ;uarks.

"undamental !osons

Bn the tandard odel, !ector (spin-1) bosons (gluons, photons, and the > and Y bosons) mediate forces, whereasthe %iggs boson (spin-*) is responsible for the intrinsic massof particles. :osons differ from fermions in the fact thatmultiple bosons can occupy the same ;uantum state (Iauli e


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cause proton decay. %owe!er, the non-obser!ation of proton decay at the uper-Ramiokande neutrino obser!atoryrules out the simplest 'Xs, including X(4) and (1*).

(upersymmetry[edit]Main article: Supersymmetry

upersymmetry e

An Introduction to Particle Detectors

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