DOCSLIB.ORG

Calorimetric Electron Telescope Mission Search for Dark Matter and Nearby Sources

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Calorimetric Electron Telescope Mission Search for Dark Matter and Nearby Sources Nuclear Instruments and Methods in Physics Research A 630 (2011) 55–57 Contents lists available at ScienceDirect Nuclear Instruments and Methods in Physics Research A journal homepage: www.elsevier.com/locate/nima Calorimetric electron telescope mission Search for dark matter and nearby sources Shoji Torii Research Institute for Science and Engineering, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan On behalf of the CALET Collaboration article info abstract Available online 14 July 2010 We are developing the CALorimetric Electron Telescope, CALET, mission for the Japanese Experiment Keywords: Module—Exposed Facility, JEM-EF, of the International Space Station, ISS. Major scientific objective is a Cosmic ray search for nearby cosmic ray sources and dark matter by carrying out a precise measurement of the Dark matter electrons in 1 GeV–20 TeV and the gamma-rays in 20 MeV-several TeV. CALET has, moreover, a Acceleration capability to measure cosmic ray H, He and heavy ions up to 1000 TeV. It will also have a function to Propagation monitor the solar activity and the gamma-ray bursts. The phase A study has started on a schedule of the launch in early 2014 by the H-II Transfer Vehicle, HTV, for a 5-year observation. & 2010 Elsevier B.V. All rights reserved. 1. Introduction Moreover, some theories predict that potential dark matter particles (Kaluza–Klein particles from extra-dimension theories, or CALET (CALrimetric Electron Telescope) is an international neutralinos predicted by supersymmetric theories) may have program for the International Space Station (ISS), which provides masses in the hundreds of GeV to TeV range. The characteristic the highest energy direct measurement of the cosmic ray signatures of such particles in both the electron and gamma ray spectrum. CALET will address many outstanding questions spectra can only be observed at the high energies reached by CALET. including (1) the nature of the sources of high energy particles and photons, through the high energy spectrum, (2) the details of particle transportation in the Galaxy, and (3) signatures of dark 2. Scientific objectives matter, in either the high energy electrons or gamma ray spectrum. It will also be capable of monitoring gamma ray It has become increasingly clear in recent years that major transients and solar modulation. changes in, and the evolution of, our own and other galaxies are The unique feature of CALET is its thick, fully active calorimeter intrinsically linked to high energy phenomena—e.g., Supernova that allows well into the TeV energy region with excellent energy explosion, Black Hole accretion, Active Galactic Nuclei (AGN) jets, resolution, coupled with a fine imaging upper calorimeter to etc.—and that these involve the acceleration of charge particles, accurately identify the starting point of electromagnetic showers. often to extreme energies. The release of these high energy particles CALET will have excellent separation between hadrons and fuels the galactic cosmic radiation, while the interactions of the electrons and between charged particles and gamma-rays. It will energetic particles produce X-ray and gamma radiation through provide unparalleled energy resolution and broad sky coverage. synchrotron, inverse Compton, and pion decay processes. CALET We anticipate being able to observe in the TeV region, for first will provide another important window on the High Energy time, an unambiguous signature of energetic particles (electrons) Universe by observing high energy electrons, hadrons, diffuse accelerated in specific sources in our local region of the Galaxy gamma-rays up to the highest energy region observed in space. and then propagating to Earth. The hadronic data provide another channel through which the details of particle acceleration in supernova remnants or other 2.1. High energy electrons sources will be investigated. Combining, for the first time, high energy, high resolution measurements of electrons, protons, Supernova explosions are generally accepted as the only sources helium, and high-Z particles provides a new tool to investigate capable of supplying the energy required to accelerate the majority cosmic accelerators in the high energy universe. of Galactic cosmic rays. Electrons provide a singularly sensitive probe of nearby high energy cosmic accelerators. Since high energy electrons lose their energy in proportion to square of the energy, by E-mail address: [email protected] synchrotron radiation and inverse-Compton scattering. As a result, 0168-9002/$ - see front matter & 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2010.06.026 56 S. Torii / Nuclear Instruments and Methods in Physics Research A 630 (2011) 55–57 higher energy through Long Duration Balloon experiments, but these are reaching a practical limit in energy. While particle acceleration associated with supernova remnant shocks appears to be the best explanation for how galactic cosmic rays below the ‘‘knee’’ achieve their high energies, the energy spectrum signatures that would provide strong support for this SNR model (i.e. charge dependent high energy spectral cutoffs) have yet to be observed. There is still no proof that SNR do, in fact, accelerate hadrons. Extending direct measurements is only possible with the long exposure of a space experiment. CALET can provide to extend the H, He and heavy ions spectrum and the B/C ratio to the unprecedented region. 2.3. Dark matter Fig. 1. Calculated electron spectrum and the expected spectrum by the CALET Over the last several decades, experimental and theoretical observation. work has essentially eliminated all known particles as dark matter candidates leaving only a few exotic species as possible [4]. Such candidates include Weakly Interacting Massive Particles (WIMPs), such as neutralinos, which annihilate and produce gamma rays and positrons as a signature. Another possibility [5] is the Kaluza–Klein (KK) particles resulting from theories invol- ving compactified extra dimensions. CALET will conduct a sensitive search for signatures of these dark mater candidates in both the electron and gamma ray spectra. The predicted signature is dependent on models with many parameters and even a non- observation by CALET will effectively constrain these parameters or eliminate some theories. Like neutralinos, KK particles can annihilate and produce an excess of both positrons and negatrons observable at Earth. Unlike neutralinos, however, direct annihilation of KK particles to e, m, t is not suppressed and consequently the KK electron signal is enhanced relative to that from neutralinos. Also, since this is a direct annihilation, it results in the appearance of monoenergetic electrons and positrons which would create a specific, easily recognizable spectral feature. Fig. 2. Anticipated anisotropy from Vela in the TeV region, and the expected A prominent increase of the positron fraction over 10 GeV, CALET observation. as reported by PAMELA [6], might be caused by such an effect. Moreover, the electron (including positron) excess in the highest energy electrons (in the TeV region) that we see very 300–800 GeV observed by ATIC, also with PPB-BETS [7], might likely originate from sources at a distance less than 1kpcfrom consistently be understood as a result of KK particles with a the Solar System and younger than 105 years. Prime candidates mass of 620 GeV [8]. On the contrary, the recent observation by are the Vela, Monogem and Cygnus Loop remnants, but other Fermi/LAT presents a harder energy spectrum with a power index possible SNR include G65.3, HB21, Geminga, S147, Loop1, SN185, of À3.04 in 20–1000 GeV without a significant enhancement and of course unidentified sources. Thus, the high energy electron around 600 GeV [9]. spectrum should exhibit structure [1] and very likely anisotropy Such a feature could be the result of a nearby source or could [2,3]. This, plus the certainty that electrons are accelerated to multi- be a signature of dark matter annihilation. Higher precision and TeV of identifying individual cosmic accelerators and determining higher statistics measurements are required to understand this the diffusion coefficient. intriguing energy range. CALET, above the Earth’s atmosphere and For a particular choice of model parameters, Fig. 1 shows the with its excellent energy resolution, will be able to investigate calculated electron spectrum compared to a compilation of previous this feature in detail. electron measurements. Investigating such structure in detail and If neutralinos are the dark matter particles, they are most directly observing, for the first time, a source or electron readily seen as a line in the high energy gamma ray spectrum. If acceleration at very high energies is only possible with CALET. At the neutralinos mass is below several 100s GeV, such a line will very high energies, significant anisotropy in the electron arrival surely be observed by Fermi/LAT. However, the superior energy directions is expected due to the local source. The anticipated resolution of CALET will enable better line-shape analysis of the anisotropy measurement by CALET is illustrated in Fig. 2 for the detected line. case in which Vela is a source of high energy electrons. 2.4. Gamma ray sources 2.2. High energy hadrons CALET’s excellent proton rejection will make it an exceptional High energy hadron spectra are important complements to the instrument for studying the diffuse high energy gamma ray information derived from electron observations. Measurements of background at energies above the upper limit of Fermi/LAT. The the cosmic ray H, He and higher Z energy spectra, including extended energy coverage for the diffuse extragalactic back- important secondary elements (e.g. B), have been pushed to every ground (EBL) should enable major progress in understanding the S. Torii / Nuclear Instruments and Methods in Physics Research A 630 (2011) 55–57 57 EBL. Moreover, the energy resolution will make CALET uniquely capable of searching for sharp lines in the high energy diffuse spectrum. For the galactic background, the CALET gamma ray sensitivity to 1 TeV should allow a potential cutoff up to approximately 100 TeV to be investigated [10].
Load more

Recommended publications
  • Foundations of Newtonian Dynamics: an Axiomatic Approach For
    Foundations of Newtonian Dynamics: 1 An Axiomatic Approach for the Thinking Student C. J. Papachristou 2 Department of Physical Sciences, Hellenic Naval Academy, Piraeus 18539, Greece Abstract. Despite its apparent simplicity, Newtonian mechanics contains conceptual subtleties that may cause some confusion to the deep-thinking student. These subtle- ties concern fundamental issues such as, e.g., the number of independent laws needed to formulate the theory, or, the distinction between genuine physical laws and deriva- tive theorems. This article attempts to clarify these issues for the benefit of the stu- dent by revisiting the foundations of Newtonian dynamics and by proposing a rigor- ous axiomatic approach to the subject. This theoretical scheme is built upon two fun- damental postulates, namely, conservation of momentum and superposition property for interactions. Newton’s laws, as well as all familiar theorems of mechanics, are shown to follow from these basic principles. 1. Introduction Teaching introductory mechanics can be a major challenge, especially in a class of students that are not willing to take anything for granted! The problem is that, even some of the most prestigious textbooks on the subject may leave the student with some degree of confusion, which manifests itself in questions like the following: • Is the law of inertia (Newton’s first law) a law of motion (of free bodies) or is it a statement of existence (of inertial reference frames)? • Are the first two of Newton’s laws independent of each other? It appears that
    [Show full text]
  • Overview of the CALET Mission to the ISS 1 Introduction
    32ND INTERNATIONAL COSMIC RAY CONFERENCE,BEIJING 2011 Overview of the CALET Mission to the ISS SHOJI TORII1,2 FOR THE CALET COLLABORATION 1Research Institute for Scinece and Engineering, Waseda University 2Space Environment Utilization Center, JAXA [email protected] DOI: 10.7529/ICRC2011/V06/0615 Abstract: The CALorimetric Electron Telescope (CALET) mission is being developed as a standard payload for the Exposure Facility of the Japanese Experiment Module (JEM/EF) on the International Space Station (ISS). The instrument consists of a segmented plastic scintillator charge measuring module, an imaging calorimeter consisting of 8 scintillating fiber planes with a total of 3 radiation lengths of tungsten plates interleaved with the fiber planes, and a total absorption calorimeter consisting of crossed PWO logs with a total depth of 27 radiation lengths. The major scientific objectives for CALET are to search for nearby cosmic ray sources and dark matter by carrying out a precise measurement of the electron spectrum (1 GeV - 20 TeV) and observing gamma rays (10 GeV - 10 TeV). CALET has a unique capability to observe electrons and gamma rays in the TeV region since the hadron rejection power is larger than 105 and the energy resolution better than 2 % above 100 GeV. CALET has also the capability to measure cosmic ray H, He and heavy nuclei up to 1000 TeV.∼ The instrument will also monitor solar activity and search for gamma ray transients. The phase B study has started, aimed at a launch in 2013 by H-II Transfer Vehicle (HTV) for a 5 year observation period on JEM/EF.
    [Show full text]
  • Chapter 11.Pdf
    Chapter 11. Kinematics of Particles Contents Introduction Rectilinear Motion: Position, Velocity & Acceleration Determining the Motion of a Particle Sample Problem 11.2 Sample Problem 11.3 Uniform Rectilinear-Motion Uniformly Accelerated Rectilinear-Motion Motion of Several Particles: Relative Motion Sample Problem 11.5 Motion of Several Particles: Dependent Motion Sample Problem 11.7 Graphical Solutions Curvilinear Motion: Position, Velocity & Acceleration Derivatives of Vector Functions Rectangular Components of Velocity and Acceleration Sample Problem 11.10 Motion Relative to a Frame in Translation Sample Problem 11.14 Tangential and Normal Components Sample Problem 11.16 Radial and Transverse Components Sample Problem 11.18 Introduction Kinematic relationships are used to help us determine the trajectory of a snowboarder completing a jump, the orbital speed of a satellite, and accelerations during acrobatic flying. Dynamics includes: Kinematics: study of the geometry of motion. Relates displacement, velocity, acceleration, and time without reference to the cause of motion. Fdownforce Fdrive Fdrag Kinetics: study of the relations existing between the forces acting on a body, the mass of the body, and the motion of the body. Kinetics is used to predict the motion caused by given forces or to determine the forces required to produce a given motion. Particle kinetics includes : • Rectilinear motion: position, velocity, and acceleration of a particle as it moves along a straight line. • Curvilinear motion : position, velocity, and acceleration of a particle as it moves along a curved line in two or three dimensions. Rectilinear Motion: Position, Velocity & Acceleration • Rectilinear motion: particle moving along a straight line • Position coordinate: defined by positive or negative distance from a fixed origin on the line.
    [Show full text]
  • Chapter 3 Motion in Two and Three Dimensions
    Chapter 3 Motion in Two and Three Dimensions 3.1 The Important Stuff 3.1.1 Position In three dimensions, the location of a particle is specified by its location vector, r: r = xi + yj + zk (3.1) If during a time interval ∆t the position vector of the particle changes from r1 to r2, the displacement ∆r for that time interval is ∆r = r1 − r2 (3.2) = (x2 − x1)i +(y2 − y1)j +(z2 − z1)k (3.3) 3.1.2 Velocity If a particle moves through a displacement ∆r in a time interval ∆t then its average velocity for that interval is ∆r ∆x ∆y ∆z v = = i + j + k (3.4) ∆t ∆t ∆t ∆t As before, a more interesting quantity is the instantaneous velocity v, which is the limit of the average velocity when we shrink the time interval ∆t to zero. It is the time derivative of the position vector r: dr v = (3.5) dt d = (xi + yj + zk) (3.6) dt dx dy dz = i + j + k (3.7) dt dt dt can be written: v = vxi + vyj + vzk (3.8) 51 52 CHAPTER 3. MOTION IN TWO AND THREE DIMENSIONS where dx dy dz v = v = v = (3.9) x dt y dt z dt The instantaneous velocity v of a particle is always tangent to the path of the particle. 3.1.3 Acceleration If a particle’s velocity changes by ∆v in a time period ∆t, the average acceleration a for that period is ∆v ∆v ∆v ∆v a = = x i + y j + z k (3.10) ∆t ∆t ∆t ∆t but a much more interesting quantity is the result of shrinking the period ∆t to zero, which gives us the instantaneous acceleration, a.
    [Show full text]
  • A Uniformly Moving and Rotating Polarizable Particle in Thermal Radiation Field: Frictional Force and Torque, Radiation and Heating
    A uniformly moving and rotating polarizable particle in thermal radiation field: frictional force and torque, radiation and heating G. V. Dedkov1 and A.A. Kyasov Nanoscale Physics Group, Kabardino-Balkarian State University, Nalchik, 360000, Russia Abstract. We study the fluctuation-electromagnetic interaction and dynamics of a small spinning polarizable particle moving with a relativistic velocity in a vacuum background of arbitrary temperature. Using the standard formalism of the fluctuation electromagnetic theory, a complete set of equations describing the decelerating tangential force, the components of the torque and the intensity of nonthermal and thermal radiation is obtained along with equations describing the dynamics of translational and rotational motion, and the kinetics of heating. An interplay between various parameters is discussed. Numerical estimations for conducting particles were carried out using MATHCAD code. In the case of zero temperature of a particle and background radiation, the intensity of radiation is independent of the linear velocity, the angular velocity orientation and the linear velocity value are independent of time. In the case of a finite background radiation temperature, the angular velocity vector tends to be oriented perpendicularly to the linear velocity vector. The particle temperature relaxes to a quasistationary value depending on the background radiation temperature, the linear and angular velocities, whereas the intensity of radiation depends on the background radiation temperature, the angular and linear velocities. The time of thermal relaxation is much less than the time of angular deceleration, while the latter time is much less than the time of linear deceleration. Key words: fluctuation-electromagnetic interaction, thermal radiation, rotating particle, frictional torque and tangential friction force 1.
    [Show full text]
  • Particle Acceleration at Interplanetary Shocks
    PARTICLE ACCELERATION AT INTERPLANETARY SHOCKS G.P. ZANK, Gang LI, and Olga VERKHOGLYADOVA Institute of Geophysics and Planetary Physics (IGPP), University of California, Riverside, CA 92521, U.S.A. ([email protected], [email protected], [email protected]) Received ; accepted Abstract. Proton acceleration at interplanetary shocks is reviewed briefly. Understanding this is of importance to describe the acceleration of heavy ions at interplanetary shocks since wave excitation, and hence particle scattering, at oblique shocks is controlled by the protons and not the heavy ions. Heavy ions behave as test particles and their acceler- ation characteristics are controlled by the properties of proton excited turbulence. As a result, the resonance condition for heavy ions introduces distinctly di®erent signatures in abundance, spectra, and intensity pro¯les, depending on ion mass and charge. Self- consistent models of heavy ion acceleration and the resulting fractionation are discussed. This includes discussion of the injection problem and the acceleration characteristics of quasi-parallel and quasi-perpendicular shocks. Keywords: Solar energetic particles, coronal mass ejections, particle acceleration 1. Introduction Understanding the problem of particle acceleration at interplanetary shocks is assuming increasing importance, especially in the context of understanding the space environment. The basic physics is thought to have been established in the late 1970s and 1980s with the seminal papers of Axford et al. (1977); Bell, (1978a,b), but detailed interplanetary observations are not easily in- terpreted in terms of the simple original models of particle acceleration at shock waves. Three fundamental aspects make the interplanetary problem more complicated than the typical astrophysical problem: the time depen- dence of the acceleration and the solar wind background; the geometry of the shock; and the long mean free path for particle transport away from the shock.
    [Show full text]
  • Estimation of Acoustic Particle Motion and Source Bearing Using a Drifting Hydrophone Array Near a River Current Turbine to Assess Disturbances to Fish
    Estimation of Acoustic Particle Motion and Source Bearing Using a Drifting Hydrophone Array Near a River Current Turbine to Assess Disturbances to Fish Paul G. Murphy A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Mechanical Engineering University of Washington 2015 Committee: Peter H. Dahl Brian Polagye David Dall’Osto Program Authorized to Offer Degree: Mechanical Engineering ©Copyright 2015 Paul Murphy University of Washington Abstract Estimation of Acoustic Particle Motion and Source Bearing Using a Drifting Hydrophone Array Near a River Current Turbine to Assess Disturbances to Fish Paul G. Murphy Co-Chair of the Supervisory Committee: Professor Peter Dahl Mechanical Engineering Co-Chair of the Supervisory Committee: Professor Brian Polagye Mechanical Engineering River hydrokinetic turbines may be an economical alternative to traditional energy sources for small communities on Alaskan rivers. However, there is concern that sound from these turbines could affect sockeye salmon (Oncorhynchus nerka), an important resource for small, subsistence based communities, commercial fisherman, and recreational anglers. The hearing sensitivity of sockeye salmon has not been quantified, but behavioral responses to sounds at frequencies less than a few hundred Hertz have been documented for Atlantic salmon (Salmo salar), and particle motion is thought to be the primary mode of stimulation. Methods of measuring acoustic particle motion are well- established, but have rarely been necessary in energetic areas, such as river and tidal current environments. In this study, the acoustic pressure in the vicinity of an operating river current turbine is measured using a freely drifting hydrophone array. Analysis of turbine sound reveals tones that vary in frequency and magnitude with turbine rotation rate, and that may sockeye salmon may sense.
    [Show full text]
  • Particle Beam Tests of the Calorimetric Electron Telescope
    33RD INTERNATIONAL COSMIC RAY CONFERENCE, RIO DE JANEIRO 2013 THE ASTROPARTICLE PHYSICS CONFERENCE Particle Beam Tests of the Calorimetric Electron Telescope TADAHISA TAMURA1, FOR THE CALET COLLABORATION. 1 Institute of Physics, Faculty of Engineering, Kanagawa university, Yokohama 221-8686 Japan [email protected] Abstract: The Calorimetric Electron Telescope (CALET) is a new mission addressing outstanding astrophysics questions including the nature of dark matter, the sources of high-energy particles and photons, and the details of particle acceleration and transport in the galaxy by measuring the high-energy spectra of electrons, nuclei, and gamma-rays. It will launch on HTV-5 (H-II Transfer Vehicle 5) in 2014 for installation on the Japanese Experiment Module–Exposed Facility (JEM-EF) of the International Space Station. The CALET collaboration is led by JAXA and includes researchers from Japan, the U.S. and Italy. The CALET Main Telescope uses a plastic scintillator charge detector followed by a 30 radiation-length (X0) deep particle calorimeter divided into a 3 X0 imaging calorimeter, with scintillating optical fibers interleaved with thin tungsten sheets, and a 27 X0 fully-active total-absorption calorimeter made of lead tungstate scintillators. CALET prototypes were tested at the CERN (European Laboratory for Particle Physics) Super Proton Synchrotron (SPS) in 2010 and 2011 using electrons to 290 GeV and protons to 350 GeV. In 2012 the CALET BEAM-TEST Model (BTM) was tested at the SPS with electrons to 300 GeV and protons to 400 GeV. The flight charge detectors were tested in 2013 at the SPS in heavy-ion beams from fragmented lead at 13 and 30 GeV/nucleon.
    [Show full text]
  • Electron Measurements with the High Energy Particle Calorimeter Telescope (Hepcat)
    PROCEEDINGS OF THE 31st ICRC, ŁOD´ Z´ 2009 1 Electron Measurements with the High Energy Particle Calorimeter Telescope (HEPCaT) J.W. Mitchell∗, T. Hams∗;1, J.F. Krizmanic∗;2, A.A. Mosieev∗;3, M. Sasaki∗;3, R.E. Streitmatter∗, J.H. Adamsy, M.J. Christly, J.W. Wattsy, T.G. Guzikz, J. Isbertz, J.P. Wefelz, C.B. Cossex, and S.J. Stochajx ∗NASA/GSFC, Greenbelt, MD 20771, USA yNASA/MSFC, Huntsville, AL 35812, USA zLouisiana State University, Baton Rouge, LA 70803, USA xNew Mexico State University, Las Cruces, NM 88003, USA Abstract. HEPCaT is designed to make direct measurements of cosmic-ray electrons to energies above 10 TeV, as part of the Orbiting Astrophysical Spectrometer in Space (OASIS) mission under study by NASA as an Astrophysics Strategic Mission Con- cept. These measurements have unmatched potential to identify high-energy particles accelerated in a local astrophysical engine and subsequently released into the Galaxy. The electron spectrum may also show signatures of dark-matter annihilation and, together with Large Hadron Collider measurements, illumi- Fig. 1: One HEPCaT Module. nate the nature of dark matter. HEPCaT uses a sam- be produced by dark-matter annihilation. Details of the pling, imaging calorimeter with silicon-strip-detector spectra and anisotropy of high-energy cosmic-ray elec- readout and a geometric acceptance of 2.5 m2 sr. trons, combined with measurements at the Large Hadron Powerful identification of the abundant hadrons is Collider and measurements of high-energy positron and achieved by imaging the longitudinal development antiproton spectra, may hold the key to revealing the and lateral distribution of particle cascades in the nature of the ubiquitous, but little understood, dark calorimeter.
    [Show full text]
  • Sound Pressure and Particle Velocity Measurements from Marine Pile Driving at Eagle Harbor Maintenance Facility, Bainbridge Island WA
    Suite 2101 – 4464 Markham Street Victoria, British Columbia, V8Z 7X8, Canada Phone: +1.250.483.3300 Fax: +1.250.483.3301 Email: [email protected] Website: www.jasco.com Sound pressure and particle velocity measurements from marine pile driving at Eagle Harbor maintenance facility, Bainbridge Island WA by Alex MacGillivray and Roberto Racca JASCO Research Ltd Suite 2101-4464 Markham St. Victoria, British Columbia V8Z 7X8 Canada prepared for Washington State Department of Transportation November 2005 TABLE OF CONTENTS 1. Introduction................................................................................................................. 1 2. Project description ...................................................................................................... 1 3. Experimental description ............................................................................................ 2 4. Methodology............................................................................................................... 4 4.1. Theory................................................................................................................. 4 4.2. Measurement apparatus ...................................................................................... 5 4.3. Data processing................................................................................................... 6 4.4. Acoustic metrics.................................................................................................. 7 4.4.1. Sound pressure levels.................................................................................
    [Show full text]
  • Particle Acceleration in Solar Flares
    A&A 471, 993–997 (2007) Astronomy DOI: 10.1051/0004-6361:20066809 & c ESO 2007 Astrophysics Particle acceleration in solar flares: linking magnetic energy release with the acceleration process C. Dauphin LUTh, Observatoire de Paris, 92195 Meudon Cedex, France e-mail: [email protected] Received 24 November 2006 / Accepted 21 May 2007 ABSTRACT Context. Particles accelerated in solar flares draw their energy from the magnetic field. The dissipative scale of the magnetic energy in the solar corona implies that the magnetic energy is transmitted to the particles through a large number of dissipative regions (DR). Aims. To finally compute the particle energy distribution, we present an approach to linking the magnetic energy release to the acceleration process that occurs in each DR . Methods. Although not directly observed, the magnetic energy release process is assumed to evolve in an SOC state that leads to the power-law behaviour of the probability distribution function for the energy released in each DR. We consider that most of the accelerated particles leave the acceleration region after one interaction, but we introduce a distribution of the particle acceleration lengths inside each acceleration region. Results. We calculate the kinetic energy distribution of the accelerated particles. Our model allows us to identify the physical process that determines each part of the particle energy distribution. Conclusions. As a conclusion, we discuss the limitations of the approach presented in this paper. Key words. Sun: flares – acceleration of particles 1. Introduction easily rise. Here, we consider that the particles are accelerated by the direct electric field that appears in such a region.
    [Show full text]
  • Base Your Answers to Questions 1 and 2 on the Graphs Below, Which Plot the Displacement of a Particle with Respect to Time
    Base your answers to questions 1 and 2 on the graphs below, which plot the displacement of a particle with respect to time. 5. The graph above represents the motion of an object traveling in a straight line as a function of time. What 1. In which of the following is the particle's acceleration is the average speed of the object during the first four constant? seconds? A) I only B) II only A) 0 m/s B) 0.2 m/s C) I and II only D) I, II, and III C) 0.5 m/s D) 1 m/s E) None of these E) 2 m/s 2. In which of the following is the rate of change of the particle's momentum zero? A) I only B) II only C) I and II only D) I, II, and III E) None of these 3. Base your answer to the following question on the graphs below, which plot the velocity of a particle with respect to time. In which of these cases is the rate of change of the 6. A simple particle's displacement constant? pendulum oscillates with amplitude A and period T, as represented on the graph above. The nature of the A) I only B) II only velocity v and acceleration a of the object at time is C) III only D) I and II only best represented by which of the following? E) None of these A) v < 0, a < 0 B) v < 0, a = 0 4. Which pair of graphs represents the same C) v < 0, a > 0 D) v = 0, a > 0 1-dimensional motion? E) v = 0, a = 0 A) B) 7.
    [Show full text]