PHYS 3446 – Lecture #16Project Assignments and tentative agendaProject DetailsProject Grading IssuesSlide 5Slide 6Slide 7Slide 8Slide 9Slide 10Super-K Event DisplaysSlide 12HW6 (due Mon 11/8)Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Wednesday, Nov. 3, 2010 PHYS 3446, Fall 2010 Andrew Brandt 1PHYS 3446 – Lecture #16Wednesday, Nov. 3, 2010Dr. Andrew BrandtParticle Detection•Time of Flight•Cerenkov Counter•Silicon•Calorimeter•Review Project assignmentsHW 7 due WedsdayProject Assignments and tentative agendaWednesday Dec. 1•Solar Neutrino Deficit Baral-Lord•Long baseline neutrino experiments (neutrino mass) Butler-Mayfield•G-2 experiments Ouyang-Wright•HERA experiments: diffraction/large rapidity gaps Gray-WooFriday Dec. 3•Quark-Gluon Plasma (RHIC) Byrd-PryorMonday Dec. 6•Higgs Boson Theory Bridges-Corbin•Standard Model+Beyond the Standard Model Higgs Boson Searches at Dzero Absher-Dean-Shumate•Supersymmetry Theory Ibarra•Blackhole/Extra Dimension Searches at ATLAS Contreras-LaRoqueWednesday, Nov. 3, 2010 2PHYS 3446, Fall 2010 Andrew BrandtProject Details•16 minute presentation+4 mins for questions (preferably powerpoint) will be done on Dec. 1, 3, 6 as outlined on previous slide. Let me know right away if some conflict. You should provide me with an outline and list of refs by Nov. 15 (10% of grade). By Nov. 22, you should provide me with a decent draft (10%), in order to get feedback in time to make modifications 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 including wikipedia); should answer most if not all of these questions as applicable. Suggested split: intro/detector results/data analysis1) what is signature involved, are there other signatures not used, why?For experimental talk 1) was experiment designed to find the result for your talk2) what detector was/will be used, describe detector’s and sub-detectors3) what was/will be importance of discovery4) who was involved names if small, institutions if large, ~how many people5) what was major source of uncertainty, statistical or systematic6) what were two most important systematic errors7) what was largest backgroundFor theory talk1) How well motivated is the theory—are there other alternative models that the LHC (or Tevatron) is sensitive to?Wednesday, Nov. 3, 2010 3PHYS 3446, Fall 2010 Andrew BrandtProject Grading Issues1) What was the subject? 2) Did the presenters describe the detectors or theory adequately?3) Did they describe the importance and/or method of the discovery/theory?4) Did they describe the measurement or calculation, errors and backgrounds if applicable?5) Was the talk interesting and comprehensible? Excessive jargon?6) Was the time management good?7) What overall grade would you give them if you were the prof? Why?Wednesday, Nov. 3, 2010 4PHYS 3446, Fall 2010 Andrew BrandtWednesday, Nov. 3, 2010 PHYS 3446, Fall 2010 Andrew Brandt 5•Scintillator + PMT can provide time resolution of 0.1 ns. –What position resolution does this corresponds to?•3cm•Array of scintillation counters can be used to measure the time of flight (TOF) of particles and obtain their velocities–What can this be used for?•To distinguish particles with the similar momentum but with different mass–How?•Measure–the momentum (p) of a particle in the magnetic field–its time of flight (t) for reaching some scintillation counter at a distance L from the point of origin of the particle—this gives the velocity–from the momentum and velocity of the particle can determine its massTime of FlightWednesday, Nov. 3, 2010 PHYS 3446, Fall 2010 Andrew Brandt 6•What is Cerenkov radiation?–Emission of coherent radiation from the excitation of atoms and molecules•When does this occur? –If a charged particle enters a dielectric medium with a speed faster than light in the medium –How is this possible?•Since the speed of light is c/n in a medium with index of refraction n, if the particle’s >1/n, its speed is larger than the local speed of light•Cerenkov light has various frequencies but blue and ultraviolet band are most interesting–Blue can be directly detected w/ standard PMTs–Ultraviolet can be converted to electrons using photosensitive molecules mixed with some gas in an ionization chamberCerenkov Detectorsn=1 n>>1Cerenkov EffectUse this property of prompt radiation to develop a fasttiming counterparticleWednesday, Nov. 3, 2010 7PHYS 3446, Fall 2010 Andrew BrandtWednesday, Nov. 3, 2010 PHYS 3446, Fall 2010 Andrew Brandt 8•TOF is the distance traveled divided by the speed of the particle, t=L/v.•Thus t in flight time of the two particle with m1 and m2 is•For known momentum, p,–Since•In non-relativistic limit,•Mass resolution of ~1% is achievable for low energiesTime of Flight (TOF)2 1t t tD = - =2 1E ELtc pc pc� �D = - =� �� �tD =2 4 2 2 2 4 2 22 12Lm c p c m c p cpc� �+ - +� �� �2 11 1Lv v� �- =� �� �2 11 1Lc b b� �-� �� �1b=1b�22mcmcgg=2mcm c cgg b=�Epc( )2 1Lm mp- =LmpDWednesday, Nov. 3, 2010 PHYS 3446, Fall 2010 Andrew Brandt 9•The angle of emission is given by •The intensity of the produced radiation per unit length of the radiator is proportional to sin2c.•For n>1, light (Cerenkov Radiation) will be emitted while for n<1, no light is observed.•One can use multiple chambers of various indices of refraction to detect Cerenkov radiation from particles of different mass but with the same momentumCerenkov Detectors1coscnqb=Wednesday, Nov. 3, 2010 PHYS 3446, Fall 2010 Andrew Brandt 10•Threshold counters–Particles with the same momentum but with different mass will start emitting Cerenkov light when the index of refraction is above a certain threshold–These counters have one type of gas but could vary the pressure in the chamber to change the index of refraction to distinguish particles–Large proton decay experiments use Cerenkov detector to detect the final state particles, such as p e+0•Differential counters–Measure the angle of emission for the given index of refraction since the emission angle for lighter particles will be larger than heavier onesCerenkov DetectorsWednesday, Nov. 3, 2010 PHYS 3446, Fall 2010 Andrew Brandt 11Super-K Event DisplaysStopping 3Wednesday, Nov.
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