PHYS 3446Lecture #19PHYS 3446 –Lecture #19Monday, Nov. 3, 2008y, ,Dr. Andrew BrandtVOTE!!!Project!1. Particle DetectionSilicon detectorsProject!•Silicon detectors• Calorimeters2. Particle AcceleratorsEl t t ti A l t•Electrostatic Accelerators• AcceleratorsShtAltMonday Nov. 3, 2008 PHYS 3446, Fall 2008Andrew Brandt1•Synchrotron AcceleratorsProject: SubjectsProject: SubjectsMuon+Kaon•Muon+Kaon• b quark (upsilon)k(J/Ψ)• c quark (J/Ψ)• Ξb (triple scoop baryon)WZ•W+Z• CP violationTl•Tau lepton• Neutrino mass (Super-Kamiokande)•Higgs (120 GeV, 180 GeV)Monday Nov. 3, 2008 PHYS 3446, Fall 2008Andrew Brandt2Project DetailsProject Details• 12 minute presentation (preferably powerpoint) will be done on Dec. 1 and Dec. 3. You should p(pypp)provide me with a draft by Nov. 24 in order to get feedback in time to make modifications. I will be in class on Nov. 26 to help anyone that needs, but there will be no formal class that day. It is important to get an early start in case you have some questions about the project as it will be a significant part of your grade At least 3 sources including original paper and not includingsignificant part of your grade. At least 3 sources including original paper and not including wikipedia. Should answer most if not all of these questions. Suggested split: intro/detector results/data analysis1)what is signature involved, are there other signatures not used, why?1)what is signature involved, are there other signatures not used, why?2) was experiment designed to find this particle3) what detector was used, describe detector’s and sub-detectors4)what was significance of discovery (mathematical)4)what was significance of discovery (mathematical)5) what was importance of discovery6) who was involved names if small, institutions if large, ~how many people7)what was major source of uncertainty statistical or systematic7)what was major source of uncertainty, statistical or systematic8) what were two most important systematic errors9) what was largest background10)etc10)etc.Monday Nov. 3, 2008 PHYS 3446, Fall 2008Andrew Brandt3No Test2• current breakdown: •Lab=20% , HW=20%, Test=40%, Project=10% Quiz=10%Lab 20% , HW 20%, Test 40%, Project 10% Quiz 10%• I proposed to skip Test2 in order to spend more time on particle physics and for people to spend more time on project• New proposal is:eitherLab=20% HW=20% Test1=30% Project=20% Quiz=10%Lab=20% , HW=20%, Test1=30%, Project=20% Quiz=10%orLab=22.2% , HW=22.2%, Test=22.2%, Project=22.2% Quiz=11.2%whichever gives each student the highest grade, this was unanimously approved, if you were not in class and really want to take a second l k b W d 11/test let me know by Weds 11/5Monday Nov. 3, 2008 PHYS 3446, Fall 2008Andrew Brandt4Project Partners and projectsAll but 2 people indicated that they were happy doing project with there current lab partners, so gp j p ,this will be the default. If you are not happy with this please email me (brandta@uta edu) and letthis, please email me ([email protected]) and let me know who your lab partner is, and I will reassign people accordingly If by Weds youreassign people accordingly. If by Weds you and your lab partner both want to work together then pick your top 3 project choices in order and email them to me and I’ll try to match people up.ypppMonday Nov. 3, 2008 PHYS 3446, Fall 2008Andrew Brandt5Semiconductor Detectors• Semiconductors can produce large signals (electron-hole pairs) for relatively small energy deposit (~3 eV)–Advantageous in measuring low energy at high resolution• Silicon strip and pixel detectors are widely used for high precision position measurements (solid state MWPC)precision position measurements (solid state MWPC)– Due to large electron-hole pair production, thin layers (200 – 300 μm) of wafers sufficient for measurements– Output signal proportional to the ionization loss– Low bias voltages sufficient to operate (avoid recombination)Cbd itdithiti (2050)thiltd–Can be deposited in thin stripes (20 –50 μm) on thin electrode– High position resolution achievable–Can be used to distinguish particles in multiple detector configurationsCan be used to distinguish particles in multiple detector configurations• So what is the catch?–Very expensive Î On the order of $30k/m2Monday Nov. 3, 2008 PHYS 3446, Fall 2008 Andrew Brandt6yp$DØ Silicon Vertex Detector21BlFDikHDik23498111675112BarrelsF-DisksH-DisksChannels 387120 258048 147456Modules 432 144 96012112Inner R 2.7 cm 2.6 cm9.5 cmOuter R 9.4 cm 10.5 cm 26 cm63One Si detector4DiskMonday Nov. 3, 2008 PHYS 3446, Fall 2008 Andrew Brandt7BarrelDisk•Magnetic measurement of momentum is not sufficientCalorimeters•Magnetic measurement of momentum is not sufficient for physics, why?Th i i f l t t–The precision for angular measurements gets worse as particles’ momenta increasesI i ti fi ld i i i i f th–Increasing magnetic field or increasing precision of the tracking device will help but will be expensiveCt tltil t–Cannot measure neutral particle momenta• How do we solve this problem?– Use a device that measures kinetic energies of particles•CalorimeterCalorimeter– A device that absorbs full kinetic energy of a particleProvides signal proportional to deposited energyMonday Nov. 3, 2008 PHYS 3446, Fall 2008 Andrew Brandt8–Provides signal proportional to deposited energyLarge scale calorimeter were developed during 1960sCalorimeters•Large scale calorimeter were developed during 1960s– For energetic cosmic rays– For particles produced in accelerator experiments•How do high energy EM (photons and electrons) andHow do high energy EM (photons and electrons) and Hadronic particles deposit their energies?El t i b t hl–Electrons: via bremsstrahlung– Photons: via electron-positron conversion, followed by bremsstrahlung of electrons and positrons–electron and photon interactions result in an electromagnetic pgshower that continues until all the initial energy is depositedMonday Nov. 3, 2008 PHYS 3446, Fall 2008 Andrew Brandt9Electron Shower ProcessPhoton, γMonday Nov. 3, 2008 PHYS 3446, Fall 2008 Andrew Brandt10Calorimeters• Hadrons are massive thus their energy deposit via brem is smallTh l h i i h h l i l l lli i•They lose their energies through multiple nuclear collisions• Incident hadron produces multiple pions and other secondary hd ithfit lliihadrons in the first collision• The secondary hadrons then
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