DOCSLIB.ORG

Introduction to Neutrino Interaction Physics NUFACT08 Summer

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Introduction to Neutrino Interaction Physics NUFACT08 Summer IntroductionIntroductionIntroduction tototo NeutrinoNeutrinoNeutrino InteractionInteractionInteraction PhysicsPhysicsPhysics NUFACT08NUFACT08NUFACT08 SummerSummerSummer SchoolSchoolSchool 11-13 June 2008 Benasque, Spain Paul Soler ReferencesReferences 1. K Zuber, “Neutrino Physics”, Institute of Physics Publishing, 2004. 2. C.H. Kim & A. Pevsner “Neutrinos in Physics and Astrophysics”, Harwood Academic Publishers, 1993. 3. K. Winter (editor), “Neutrino Physics”, Cambridge University Press (2 nd edition), 2000. 4. R.N. Mohapatra, P.B. Pal, “Massive Neutrinos in Physics and Astrophysics”, World Scientific (2 nd edition), 1998. 5. H.V. Klapdor-Kleingrothaus & K. Zuber, “Particle Astrophysics”, Institute of Physics Publishing, 1997. 6. K. McFarland, Neutrino Interaction Physics, lectures at SUSSP61, St Andrews, June 2006, (To be published in Proceedings SUSSP61, Taylor & Francis, 2008). Neutrino Interaction Physics 2 NUFACT08 Summer School ContentsContents 1. History and Introduction 2. Neutrino Electron Scattering 3. Neutrino Nucleon Deep-Inelastic Scattering 4. Quasi-elastic, Resonant, Coherent and Diffractive Scattering 5. Nuclear Effects Neutrino Interaction Physics 3 NUFACT08 Summer School 1. History and Introduction 1.1 Fermi Theory 1.2 Neutrino discovery 1.3 Parity violation and V-A theory 1.4 Neutral currents 1.5 Standard model neutrino interactions Neutrino Interaction Physics 4 NUFACT08 Summer School 1.11.1 FermiFermi theorytheory ofof betabeta decaydecay (1932)(1932) Existence of a point-like four fermion interaction (Fermi , 1932): − n e − n → p + e +ν e p ν e Lagrangian of the interaction: G L(x) = − F [φ (x)γ µφ (x)][φ (x)γ φ (x)] 2 p n e µ ν −5 −2 GF = Fermi coupling constant = .1( 16637 ± .0 00001 )×10 GeV Gamow-Teller interaction when final spin different to initial nucleus: GF i L(x) = − ∑[φ p (x)Γ φn (x)][φe (x)Γiφν (x)]+ h c.. 2 i Possible interactions: Γi = ,1 γ 5 ,γ µ ,γ 5γ µ ,σ µν = S, P,V , A,T Neutrino Interaction Physics 5 NUFACT08 Summer School FirstFirst neutrinoneutrino crosscross --sectionsection calculationcalculation Bethe-Peierls (1934): calculation of first cross-section for inverse beta reaction + or − using Fermi theory ν e + p → n + e ν e + n → p + e −44 2 νe σ ≈ 5×10 cm for E(ν ) = 2 MeV Accurate to factor 2 σ b Conversion from natural units: hc =197 3. MeV ⋅ fm p 2 −27 2 2 Cross-section: multiply by (hc) = .0 3894 ×10 GeV ⋅cm Mean free path of antineutrino in water: 1 λ = ≈ 5.1 ×10 21 cm ≈1600 light − years nσ num. free protons N n = ≈ 2 A ρ volume A 2 ×6×10 23 In water: n = = 7.6 ×10 22 cm −3 18 Probability of interaction: L L P =1− exp − ≈ = 7.6 ×10 −20 (m water )−1 λ λ Need very intense source of antineutrinos to detect inverse beta reaction. Neutrino Interaction Physics 6 NUFACT08 Summer School 1.21.2 NeutrinoNeutrino discoverydiscovery (1956)(1956) + Reines and Cowan detect ν e + p → n + e in 1953 (Hanford) (discovery confirmed 1956 in Savannah River): – Detection of two back-to-back γs from prompt signal e +e- ->γγ at t=0. – Neutron thermalization: neutron capture in Cd, emission of late γs <t>~ 20 ms γ γ γ Scintillator γ n e + H2O + CdCl 2 γ Scintillator ν Publication Science 1956: σσσ= 6 x10 -44 cm 2 ±±± 25% (within 5% expected) 1956: parity violation discovery increases theory cross-section: σσσ=(10 ±±±1.7)x10 -44 cm 2 Reanalysis data in 1960: σσσ= (12+7-4) x10 -44 cm 2 Nobel prize Reines 1995 4200 l scintillator Neutrino Interaction Physics 7 NUFACT08 Summer School 1.31.3 ParityParity violationviolation andand VV --AA Parity violation in weak decays postulated by Lee & Yang in 1950 Parity violation confirmed through forward-backward asymmetry of polarized 60 Co ( Wu , 1957). 60 60 * − Co → Ni + e +ν e More electrons emitted in direction opposite to 60 Co spins, implying maximal parity violation r r r r σ ⋅ p P σ ⋅(− p) Helicity operator: H = r → r = −H p p Projects spin along direction of motion Neutrino Interaction Physics 8 NUFACT08 Summer School 1.31.3 ParityParity violationviolation andand VV --AA Goldhaber, Grodzins, Sunyar (1958) measure helicity of neutrino from K capture of 152 Eu: 152 − − 152 * − Eu 0( ) + e → Sm 1( ) +ν e 152 Sm * 1( − )→152 Sm * 0( + ) +γ pγ=-pν σγ=-σν Hγ=Hν Asymmetry of photon spectrum in magnetic field determines helicity of νe: H (ν e ) = −1⇒ H (ν e ) = +1 Neutrinos are “left-handed” Antineutrinos are “right-handed” Neutrino Interaction Physics 9 NUFACT08 Summer School 1.31.3 ParityParity violationviolation andand VV --AA Left and right handed projection operators: 1 1 ν = Pν = 1( −γ )ν ν = P ν = 1( +γ )ν L L 2 5 R R 2 5 0 1 2 3 Chirality operator: γ 5 = iγ γ γ γ same as helicity operator for massless neutrinos ( E=p ). γ 5ν L = Hν L = −ν L γ 5ν R = Hν R = +ν R If only νL interact and ν_____R do not interact, then Γi have to transform as: eΓiν → ()()PLe Γi PLν = ePRΓi PLν 1 1 V : P γ µP = γ µ ()1− γ A :P γ µγ P = − γ µ ()1− γ R L 2 5 R 5 L 2 5 The only possible coupling is V-A, due to maximal parity violation in weak interactions ( Feynman, Gell-Mann , 1958): GF µ LV −A = − [φ pγ 1( − g Aγ 5 )φn ][φeγ µ 1( −γ 5 )φν ]with g A = − .1 2573 ± .0 0028 2 (determined empirically) Neutrino Interaction Physics 10 NUFACT08 Summer School 1.41.4 NeutralNeutral currentscurrents Two types of weak interaction: charged current (CC) and neutral current (NC) from electroweak theory of Glashow, Weinberg, Salam. 0 W ± Z First example of NC observed in 1973, inside the Gargamelle bubble chamber filled with freon (CF 3Br): no muon! ν µ ν µ Z 0 N X ν µ + N →ν µ + X Neutrino Interaction Physics 11 NUFACT08 Summer School 1.51.5 StandardStandard ModelModel NeutrinoNeutrino InteractionsInteractions Lagrangian for electroweak interactions: g L = i [j(+)W µ + j (−)W µ + ]+ i[g cos θ j )3( − g sin' θ j (Y )2/ ]Z µ + int 2 µ µ W µ W µ )3( (Y )2/ µ + i[]g sin θW jµ + g'cos θW jµ A 1st term: charged current interactions (W +, W - exchange) 2nd term: neutral current interactions (Z 0 exchange) 3rd term:electromagnetic interactions (photon exchange) Electron charge: e = g sin θW = g'cos θW e.m. )3( (Y )2/ rd 3 term: ej µ = e( jµ + jµ ) (neutrinos only couple to W ± and Z 0) Neutrino Interaction Physics 12 NUFACT08 Summer School S.M.S.M. interactionsinteractions (cont)(cont) A) Neutrino electron interaction g (+) µ (−) µ + g (Z ) µ e.m Lint = i [jµ W + jµ W ]+ i jµ Z + iej µ 2 2cos θW 1 j (+) =ν γ e = ν γ 1( −γ )e Where: µ e,L µ L 2 e µ 5 1 j (−) = e γ ν = eγ 1( −γ )ν µ L µ e,L 2 µ 5 e (Z ) )3( 2 e.m jµ = (2 jµ − sin θW jµ ) = 2 =ν e,Lγ µν e,L − eLγ µ eL + 2sin θW eγ µ e = 1 1 = ν γ 1( −γ )ν − eγ 1( −γ )e + 2sin 2 θ eγ e 2 e µ 5 e 2 µ 5 W µ 1 ⇒ j(Z ) = ν γ 1( −γ )ν + eγ (g − g γ )e µ 2 e µ 5 e µ V A 5 1 1 With: g = − + 2sin 2 θ g = − V 2 W A 2 Neutrino Interaction Physics 13 NUFACT08 Summer School S.M.S.M. interactionsinteractions (cont)(cont) B) Quark weak interactions g (+) µ (−) µ + g (Z ) µ e.m Lint = i [jµ W + jµ W ]+ i jµ Z + iej µ 2 2cos θW 1 Where: j (+) = uγ 1( −γ )d µ 2 µ 5 1 j (−) = dγ 1( −γ )u µ 2 µ 5 (Z ) jµ = uγ µ (Au − Buγ 5 )u + dγ µ (Ad − Bdγ 5 )d With: 1 4 1 A = − sin 2 θ B = u 2 3 W u 2 1 1 2 2 A = − + sin θ Bd = − d 2 3 W 2 Neutrino Interaction Physics 14 NUFACT08 Summer School S.M.S.M. interactionsinteractions (cont)(cont) After introducing Higgs field and spontaneous symmetry breaking: 2 2 4 LHiggs = − Dµφ − µ φ − λ φ Masses: mH = 2λv 2 gv 2 m ± g 2 m ± = W W = = cos θ 2 2 2 W mZ 0 g + g' g 2 + g'2 m 0 = v Z 2 − /1 2 Vacuum expectation value: v = ( 2GF ) ≈ 246 GeV Effective Hamiltonian: g 2 g 2 H = j (+)µ j (−) + h.c. + j (Z )µ j (Z ) = eff 2 []µ 2 2 µ 4mW 8mZ cos θW G = F [2 j(+)µ j (−) + h c.. + j(Z )µ j(Z ) ] 2 µ µ Neutrino Interaction Physics 15 NUFACT08 Summer School S.M.S.M. interactionsinteractions (cont)(cont) The vector boson masses are then predicted: G g 2 e2 4πα F = = = α = /1 137 .036 2 2 2 2 2 2 8mW 8mW sin θW 8mW sin θW mW = 80 .450 ± .0 058 GeV Masses: 2 m = 91 .1876 ± .0 0021 GeV 2 37 .2805 Z mW = sin θ 2 W sin θW = .0 22280 ± .0 00035 Need radiative corrections: 37 .2805 mW = /1 2 sin θW 1( − ∆r ) with ∆r ≈ .0 03630 ± .0 0011 for m t = 172 7. GeV mH = 117 GeV yields : mW = 80 51. ± 11.0 GeV Neutrino Interaction Physics 16 NUFACT08 Summer School 2. Neutrino Electron Scattering 2.1 Charged current 2.2 Neutral current 2.3 Interference charged and neutral current 2.4 Mass suppression 2.5 Number of neutrinos Neutrino Interaction Physics 17 NUFACT08 Summer School 2.12.1 NeutrinoNeutrino --electronelectron CCCC scatteringscattering − − Only charged current: ν µ + e →ν e + µ (Inverse Muon Decay) − GF µ ν µ µ H = [ν γ 1( − γ )µ][eγ 1( − γ )ν ] eff 2 µ 5 µ 5 e − s = p + p 2= 2m E (in LAB ) W ( ν µ e ) e ν µ t = q 2 = −Q2 = p − p 2 − ( ν µ µ ) Inelasticity variable e ν e p ⋅ p − p E − E (0<y<1) e ( ν µ µ ) ν µ µ Total spin J=0 y = = (in LAB ) p ⋅ p E e ν µ ν µ dσ (ν e− ) G 2 m 4 s G 2 m 4 CC µ = F W ⇒ σ (ν e− ) = F W dQ 2 2 2 2 2 CC µ ∫ 2 2 2 dQ dy π (Q + mW ) 0 π (Q + mW ) Total cross-section (ignoring mass terms): Measurement CHARM-II: 2 2 E − GF s 2GF me − −41 2 σ (ν e ) ≈ = E (in LAB ) σ(ν µe ) = ().1 651 ± .0 093 ×10 cm CC µ ν µ 1GeV π π (cross-section proportional to energy!) 2 2 2GF me ()hc Eν Eν hc = 197 33.
Load more

Recommended publications
  • The Five Common Particles
    The Five Common Particles The world around you consists of only three particles: protons, neutrons, and electrons. Protons and neutrons form the nuclei of atoms, and electrons glue everything together and create chemicals and materials. Along with the photon and the neutrino, these particles are essentially the only ones that exist in our solar system, because all the other subatomic particles have half-lives of typically 10-9 second or less, and vanish almost the instant they are created by nuclear reactions in the Sun, etc. Particles interact via the four fundamental forces of nature. Some basic properties of these forces are summarized below. (Other aspects of the fundamental forces are also discussed in the Summary of Particle Physics document on this web site.) Force Range Common Particles It Affects Conserved Quantity gravity infinite neutron, proton, electron, neutrino, photon mass-energy electromagnetic infinite proton, electron, photon charge -14 strong nuclear force ≈ 10 m neutron, proton baryon number -15 weak nuclear force ≈ 10 m neutron, proton, electron, neutrino lepton number Every particle in nature has specific values of all four of the conserved quantities associated with each force. The values for the five common particles are: Particle Rest Mass1 Charge2 Baryon # Lepton # proton 938.3 MeV/c2 +1 e +1 0 neutron 939.6 MeV/c2 0 +1 0 electron 0.511 MeV/c2 -1 e 0 +1 neutrino ≈ 1 eV/c2 0 0 +1 photon 0 eV/c2 0 0 0 1) MeV = mega-electron-volt = 106 eV. It is customary in particle physics to measure the mass of a particle in terms of how much energy it would represent if it were converted via E = mc2.
    [Show full text]
  • Lepton Flavor and Number Conservation, and Physics Beyond the Standard Model
    Lepton Flavor and Number Conservation, and Physics Beyond the Standard Model Andr´ede Gouv^ea1 and Petr Vogel2 1 Department of Physics and Astronomy, Northwestern University, Evanston, Illinois, 60208, USA 2 Kellogg Radiation Laboratory, Caltech, Pasadena, California, 91125, USA April 1, 2013 Abstract The physics responsible for neutrino masses and lepton mixing remains unknown. More ex- perimental data are needed to constrain and guide possible generalizations of the standard model of particle physics, and reveal the mechanism behind nonzero neutrino masses. Here, the physics associated with searches for the violation of lepton-flavor conservation in charged-lepton processes and the violation of lepton-number conservation in nuclear physics processes is summarized. In the first part, several aspects of charged-lepton flavor violation are discussed, especially its sensitivity to new particles and interactions beyond the standard model of particle physics. The discussion concentrates mostly on rare processes involving muons and electrons. In the second part, the sta- tus of the conservation of total lepton number is discussed. The discussion here concentrates on current and future probes of this apparent law of Nature via searches for neutrinoless double beta decay, which is also the most sensitive probe of the potential Majorana nature of neutrinos. arXiv:1303.4097v2 [hep-ph] 29 Mar 2013 1 1 Introduction In the absence of interactions that lead to nonzero neutrino masses, the Standard Model Lagrangian is invariant under global U(1)e × U(1)µ × U(1)τ rotations of the lepton fields. In other words, if neutrinos are massless, individual lepton-flavor numbers { electron-number, muon-number, and tau-number { are expected to be conserved.
    [Show full text]
  • The Story of Large Electron Positron Collider 1
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Publications of the IAS Fellows GENERAL ç ARTICLE The Story of Large Electron Positron Collider 1. Fundamental Constituents of Matter S N Ganguli I nt roduct ion The story of the large electron positron collider, in short LEP, is linked intimately with our understanding of na- ture'sfundamental particlesand theforcesbetween them. We begin our story by giving a brief account of three great discoveries that completely changed our thinking Som Ganguli is at the Tata Institute of Fundamental and started a new ¯eld we now call particle physics. Research, Mumbai. He is These discoveries took place in less than three years currently participating in an during 1895 to 1897: discovery of X-rays by Wilhelm experiment under prepara- Roentgen in 1895, discovery of radioactivity by Henri tion for the Large Hadron Becquerel in 1896 and the identi¯cation of cathode rays Collider (LHC) at CERN, Geneva. He has been as electrons, a fundamental constituent of atom by J J studying properties of Z and Thomson in 1897. It goes without saying that these dis- W bosons produced in coveries were rewarded by giving Nobel Prizes in 1901, electron-positron collisions 1903 and 1906, respectively. X-rays have provided one at the Large Electron of the most powerful tools for investigating the struc- Positron Collider (LEP). During 1970s and early ture of matter, in particular the study of molecules and 1980s he was studying crystals; it is also an indispensable tool in medical diag- production and decay nosis.
    [Show full text]
  • A Discussion on Characteristics of the Quantum Vacuum
    A Discussion on Characteristics of the Quantum Vacuum Harold \Sonny" White∗ NASA/Johnson Space Center, 2101 NASA Pkwy M/C EP411, Houston, TX (Dated: September 17, 2015) This paper will begin by considering the quantum vacuum at the cosmological scale to show that the gravitational coupling constant may be viewed as an emergent phenomenon, or rather a long wavelength consequence of the quantum vacuum. This cosmological viewpoint will be reconsidered on a microscopic scale in the presence of concentrations of \ordinary" matter to determine the impact on the energy state of the quantum vacuum. The derived relationship will be used to predict a radius of the hydrogen atom which will be compared to the Bohr radius for validation. The ramifications of this equation will be explored in the context of the predicted electron mass, the electrostatic force, and the energy density of the electric field around the hydrogen nucleus. It will finally be shown that this perturbed energy state of the quan- tum vacuum can be successfully modeled as a virtual electron-positron plasma, or the Dirac vacuum. PACS numbers: 95.30.Sf, 04.60.Bc, 95.30.Qd, 95.30.Cq, 95.36.+x I. BACKGROUND ON STANDARD MODEL OF COSMOLOGY Prior to developing the central theme of the paper, it will be useful to present the reader with an executive summary of the characteristics and mathematical relationships central to what is now commonly referred to as the standard model of Big Bang cosmology, the Friedmann-Lema^ıtre-Robertson-Walker metric. The Friedmann equations are analytic solutions of the Einstein field equations using the FLRW metric, and Equation(s) (1) show some commonly used forms that include the cosmological constant[1], Λ.
    [Show full text]
  • 12 from Neutral Currents to Weak Vector Bosons
    12 From neutral currents to weak vector bosons The unification of weak and electromagnetic interactions, 1973{1987 Fermi's theory of weak interactions survived nearly unaltered over the years. Its basic structure was slightly modified by the addition of Gamow-Teller terms and finally by the determination of the V-A form, but its essence as a four fermion interaction remained. Fermi's original insight was based on the analogy with elec- tromagnetism; from the start it was clear that there might be vector particles transmitting the weak force the way the photon transmits the electromagnetic force. Since the weak interaction was of short range, the vector particle would have to be heavy, and since beta decay changed nuclear charge, the particle would have to carry charge. The weak (or W) boson was the object of many searches. No evidence of the W boson was found in the mass region up to 20 GeV. The V-A theory, which was equivalent to a theory with a very heavy W , was a satisfactory description of all weak interaction data. Nevertheless, it was clear that the theory was not complete. As described in Chapter 6, it predicted cross sections at very high energies that violated unitarity, the basic principle that says that the probability for an individual process to occur must be less than or equal to unity. A consequence of unitarity is that the total cross section for a process with 2 angular momentum J can never exceed 4π(2J + 1)=pcm. However, we have seen that neutrino cross sections grow linearly with increasing center of mass energy.
    [Show full text]
  • The Standard Model Part II: Charged Current Weak Interactions I
    Prepared for submission to JHEP The Standard Model Part II: Charged Current weak interactions I Keith Hamiltona aDepartment of Physics and Astronomy, University College London, London, WC1E 6BT, UK E-mail: [email protected] Abstract: Rough notes on ... Introduction • Relation between G and g • F W Leptonic CC processes, ⌫e− scattering • Estimated time: 3 hours ⇠ Contents 1 Charged current weak interactions 1 1.1 Introduction 1 1.2 Leptonic charge current process 9 1 Charged current weak interactions 1.1 Introduction Back in the early 1930’s we physicists were puzzled by nuclear decay. • – In particular, the nucleus was observed to decay into a nucleus with the same mass number (A A) and one atomic number higher (Z Z + 1), and an emitted electron. ! ! – In such a two-body decay the energy of the electron in the decay rest frame is constrained by energy-momentum conservation alone to have a unique value. – However, it was observed to have a continuous range of values. In 1930 Pauli first introduced the neutrino as a way to explain the observed continuous energy • spectrum of the electron emitted in nuclear beta decay – Pauli was proposing that the decay was not two-body but three-body and that one of the three decay products was simply able to evade detection. To satisfy the history police • – We point out that when Pauli first proposed this mechanism the neutron had not yet been discovered and so Pauli had in fact named the third mystery particle a ‘neutron’. – The neutron was discovered two years later by Chadwick (for which he was awarded the Nobel Prize shortly afterwards in 1935).
    [Show full text]
  • Lesson 1: the Single Electron Atom: Hydrogen
    Lesson 1: The Single Electron Atom: Hydrogen Irene K. Metz, Joseph W. Bennett, and Sara E. Mason (Dated: July 24, 2018) Learning Objectives: 1. Utilize quantum numbers and atomic radii information to create input files and run a single-electron calculation. 2. Learn how to read the log and report files to obtain atomic orbital information. 3. Plot the all-electron wavefunction to determine where the electron is likely to be posi- tioned relative to the nucleus. Before doing this exercise, be sure to read through the Ins and Outs of Operation document. So, what do we need to build an atom? Protons, neutrons, and electrons of course! But the mass of a proton is 1800 times greater than that of an electron. Therefore, based on de Broglie’s wave equation, the wavelength of an electron is larger when compared to that of a proton. In other words, the wave-like properties of an electron are important whereas we think of protons and neutrons as particle-like. The separation of the electron from the nucleus is called the Born-Oppenheimer approximation. So now we need the wave-like description of the Hydrogen electron. Hydrogen is the simplest atom on the periodic table and the most abundant element in the universe, and therefore the perfect starting point for atomic orbitals and energies. The compu- tational tool we are going to use is called OPIUM (silly name, right?). Before we get started, we should know what’s needed to create an input file, which OPIUM calls a parameter files. Each parameter file consist of a sequence of ”keyblocks”, containing sets of related parameters.
    [Show full text]
  • Discovery of Weak Neutral Currents∗
    Discovery of Weak Neutral Currents∗ Dieter Haidt Emeritus at DESY, Hamburg 1 Introduction Following the tradition of previous Neutrino Conferences the opening talk is devoted to a historic event, this year to the epoch-making discovery of Weak Neutral Currents four decades ago. The major laboratories joined in a worldwide effort to investigate this new phenomenon. It resulted in new accelerators and colliders pushing the energy frontier from the GeV to the TeV regime and led to the development of new, almost bubble chamber like, general purpose detectors. While the Gargamelle collaboration consisted of seven european laboratories and was with nearly 60 members one of the biggest collaborations at the time, the LHC collaborations by now have grown to 3000 members coming from all parts in the world. Indeed, High Energy Physics is now done on a worldwide level thanks to net working and fast communications. It seems hardly imaginable that 40 years ago there was no handy, no world wide web, no laptop, no email and program codes had to be punched on cards. Before describing the discovery of weak neutral currents as such and the cir- cumstances how it came about a brief look at the past four decades is anticipated. The history of weak neutral currents has been told in numerous reviews and spe- cialized conferences. Neutral currents have since long a firm place in textbooks. The literature is correspondingly rich - just to point out a few references [1, 2, 3, 4]. 2 Four decades Figure 1 sketches the glorious electroweak way originating in the discovery of weak neutral currents by the Gargamelle Collaboration and followed by the series of eminent discoveries.
    [Show full text]
  • 1.1. Introduction the Phenomenon of Positron Annihilation Spectroscopy
    PRINCIPLES OF POSITRON ANNIHILATION Chapter-1 __________________________________________________________________________________________ 1.1. Introduction The phenomenon of positron annihilation spectroscopy (PAS) has been utilized as nuclear method to probe a variety of material properties as well as to research problems in solid state physics. The field of solid state investigation with positrons started in the early fifties, when it was recognized that information could be obtained about the properties of solids by studying the annihilation of a positron and an electron as given by Dumond et al. [1] and Bendetti and Roichings [2]. In particular, the discovery of the interaction of positrons with defects in crystal solids by Mckenize et al. [3] has given a strong impetus to a further elaboration of the PAS. Currently, PAS is amongst the best nuclear methods, and its most recent developments are documented in the proceedings of the latest positron annihilation conferences [4-8]. PAS is successfully applied for the investigation of electron characteristics and defect structures present in materials, magnetic structures of solids, plastic deformation at low and high temperature, and phase transformations in alloys, semiconductors, polymers, porous material, etc. Its applications extend from advanced problems of solid state physics and materials science to industrial use. It is also widely used in chemistry, biology, and medicine (e.g. locating tumors). As the process of measurement does not mostly influence the properties of the investigated sample, PAS is a non-destructive testing approach that allows the subsequent study of a sample by other methods. As experimental equipment for many applications, PAS is commercially produced and is relatively cheap, thus, increasingly more research laboratories are using PAS for basic research, diagnostics of machine parts working in hard conditions, and for characterization of high-tech materials.
    [Show full text]
  • Introduction to Subatomic- Particle Spectrometers∗
    IIT-CAPP-15/2 Introduction to Subatomic- Particle Spectrometers∗ Daniel M. Kaplan Illinois Institute of Technology Chicago, IL 60616 Charles E. Lane Drexel University Philadelphia, PA 19104 Kenneth S. Nelsony University of Virginia Charlottesville, VA 22901 Abstract An introductory review, suitable for the beginning student of high-energy physics or professionals from other fields who may desire familiarity with subatomic-particle detection techniques. Subatomic-particle fundamentals and the basics of particle in- teractions with matter are summarized, after which we review particle detectors. We conclude with three examples that illustrate the variety of subatomic-particle spectrom- eters and exemplify the combined use of several detection techniques to characterize interaction events more-or-less completely. arXiv:physics/9805026v3 [physics.ins-det] 17 Jul 2015 ∗To appear in the Wiley Encyclopedia of Electrical and Electronics Engineering. yNow at Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723. 1 Contents 1 Introduction 5 2 Overview of Subatomic Particles 5 2.1 Leptons, Hadrons, Gauge and Higgs Bosons . 5 2.2 Neutrinos . 6 2.3 Quarks . 8 3 Overview of Particle Detection 9 3.1 Position Measurement: Hodoscopes and Telescopes . 9 3.2 Momentum and Energy Measurement . 9 3.2.1 Magnetic Spectrometry . 9 3.2.2 Calorimeters . 10 3.3 Particle Identification . 10 3.3.1 Calorimetric Electron (and Photon) Identification . 10 3.3.2 Muon Identification . 11 3.3.3 Time of Flight and Ionization . 11 3.3.4 Cherenkov Detectors . 11 3.3.5 Transition-Radiation Detectors . 12 3.4 Neutrino Detection . 12 3.4.1 Reactor Neutrinos . 12 3.4.2 Detection of High Energy Neutrinos .
    [Show full text]
  • Neutrino Opacity I. Neutrino-Lepton Scattering*
    PHYSICAL REVIEW VOLUME 136, NUMBER 4B 23 NOVEMBER 1964 Neutrino Opacity I. Neutrino-Lepton Scattering* JOHN N. BAHCALL California Institute of Technology, Pasadena, California (Received 24 June 1964) The contribution of neutrino-lepton scattering to the total neutrino opacity of matter is investigated; it is found that, contrary to previous beliefs, neutrino scattering dominates the neutrino opacity for many astro­ physically important conditions. The rates for neutrino-electron scattering and antineutrino-electron scatter­ ing are given for a variety of conditions, including both degenerate and nondegenerate gases; the rates for some related reactions are also presented. Formulas are given for the mean scattering angle and the mean energy loss in neutrino and antineutrino scattering. Applications are made to the following problems: (a) the detection of solar neutrinos; (b) the escape of neutrinos from stars; (c) neutrino scattering in cosmology; and (d) energy deposition in supernova explosions. I. INTRODUCTION only been discussed for the special situation of electrons 13 14 XPERIMENTS1·2 designed to detect solar neu­ initially at rest. · E trinos will soon provide crucial tests of the theory In this paper, we investigate the contribution of of stellar energy generation. Other neutrino experiments neutrino-lepton scattering to the total neutrino opacity have been suggested as a test3 of a possible mechanism of matter and show, contrary to previous beliefs, that for producing the high-energy electrons that are inferred neutrino-lepton scattering dominates the neutrino to exist in strong radio sources and as a means4 for opacity for many astrophysically important conditions. studying the high-energy neutrinos emitted in the decay Here, neutrino opacity is defined, analogously to photon of cosmic-ray secondaries.
    [Show full text]
  • A Young Physicist's Guide to the Higgs Boson
    A Young Physicist’s Guide to the Higgs Boson Tel Aviv University Future Scientists – CERN Tour Presented by Stephen Sekula Associate Professor of Experimental Particle Physics SMU, Dallas, TX Programme ● You have a problem in your theory: (why do you need the Higgs Particle?) ● How to Make a Higgs Particle (One-at-a-Time) ● How to See a Higgs Particle (Without fooling yourself too much) ● A View from the Shadows: What are the New Questions? (An Epilogue) Stephen J. Sekula - SMU 2/44 You Have a Problem in Your Theory Credit for the ideas/example in this section goes to Prof. Daniel Stolarski (Carleton University) The Usual Explanation Usual Statement: “You need the Higgs Particle to explain mass.” 2 F=ma F=G m1 m2 /r Most of the mass of matter lies in the nucleus of the atom, and most of the mass of the nucleus arises from “binding energy” - the strength of the force that holds particles together to form nuclei imparts mass-energy to the nucleus (ala E = mc2). Corrected Statement: “You need the Higgs Particle to explain fundamental mass.” (e.g. the electron’s mass) E2=m2 c4+ p2 c2→( p=0)→ E=mc2 Stephen J. Sekula - SMU 4/44 Yes, the Higgs is important for mass, but let’s try this... ● No doubt, the Higgs particle plays a role in fundamental mass (I will come back to this point) ● But, as students who’ve been exposed to introductory physics (mechanics, electricity and magnetism) and some modern physics topics (quantum mechanics and special relativity) you are more familiar with..
    [Show full text]