How and Why to Go Beyond the Discovery of the Higgs Boson
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Neutron Stars
Chandra X-Ray Observatory X-Ray Astronomy Field Guide Neutron Stars Ordinary matter, or the stuff we and everything around us is made of, consists largely of empty space. Even a rock is mostly empty space. This is because matter is made of atoms. An atom is a cloud of electrons orbiting around a nucleus composed of protons and neutrons. The nucleus contains more than 99.9 percent of the mass of an atom, yet it has a diameter of only 1/100,000 that of the electron cloud. The electrons themselves take up little space, but the pattern of their orbit defines the size of the atom, which is therefore 99.9999999999999% Chandra Image of Vela Pulsar open space! (NASA/PSU/G.Pavlov et al. What we perceive as painfully solid when we bump against a rock is really a hurly-burly of electrons moving through empty space so fast that we can't see—or feel—the emptiness. What would matter look like if it weren't empty, if we could crush the electron cloud down to the size of the nucleus? Suppose we could generate a force strong enough to crush all the emptiness out of a rock roughly the size of a football stadium. The rock would be squeezed down to the size of a grain of sand and would still weigh 4 million tons! Such extreme forces occur in nature when the central part of a massive star collapses to form a neutron star. The atoms are crushed completely, and the electrons are jammed inside the protons to form a star composed almost entirely of neutrons. -
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. -
Photons from 252Cf and 241Am-Be Neutron Sources H
Neutronenbestrahlungsraum Calibration Laboratory LB6411 Am-Be Quelle [email protected] Photons from 252Cf and 241Am-Be neutron sources H. Hoedlmoser, M. Boschung, K. Meier and S. Mayer Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland At the accredited PSI calibration laboratory neutron reference fields traceable to the standards of the Physikalisch-Technische Bundesanstalt (PTB) in Germany are available for the calibration of ambient and personal dose equivalent (rate) meters and passive dosimeters. The photon contribution to H*(10) in the neutron fields of the 252Cf and 241Am-Be sources was measured using various photon dose rate meters and active and passive dosimeters. Measuring photons from a neutron source involves considerable uncertainties due to the presence of neutrons, due to a non-zero neutron sensitivity of the photon detector and due to the energy response of the photon detectors. Therefore eight independent detectors and methods were used to obtain a reliable estimate for the photon contribution as an average of the individual methods. For the 241Am-Be source a photon contribution of approximately 4.9% was determined and for the 252Cf source a contribution of 3.6%. 1) Photon detectors 2) Photons from 252Cf and 241Am-Be neutron sources Figure 1 252Cf decays through -emission (~97%) and through spontaneous fission (~3%) with a half-life of 2.65 y. Both processes are accompanied by photon radiation. Furthermore the spectrum of fission products contains radioactive elements that produce additional gamma photons. In the 241Am-Be source 241Am decays through -emission and various low energy emissions: 241Am237Np + + with a half life of 432.6 y. -
NRP-3 the Effect of Beryllium Interaction with Fast Neutrons on the Reactivity of Etrr-2 Research Reactor
Seventh Conference of Nuclear Sciences & Applications 6-10 February 2000, Cairo, Egypt NRP-3 The Effect Of Beryllium Interaction With Fast Neutrons On the Reactivity Of Etrr-2 Research Reactor Moustafa Aziz and A.M. EL Messiry National Center for Nuclear Safety Atomic Energy Autho , Cairo , Egypt ABSTRACT The effect of beryllium interactions with fast neutrons is studied for Etrr_2 research reactors. Isotope build up inside beryllium blocks is calculated under different irradiation times. A new model for the Etrr_2 research reactor is designed using MCNP code to calculate the reactivity and flux change of the reactor due to beryllium poison. Key words: Research Reactors , Neutron Flux , Beryllium Blocks, Fast Neutrons and Reactivity INTRODUCTION Beryllium irradiated by fast neutrons with energies in the range 0.7-20 Mev undergoes (n,a) and (n,2n) reactions resulting in subsequent formation of the isotopes lithium (Li-6), tritium (H-3) and helium (He-3 and He-4 ). Beryllium interacts with fast neutrons to produce 6He that decay 6 6 ( T!/2 =0.8 s) to produce Li . Li interacts with neutron to produce tritium which suffer /? (T1/2 = 12.35 year) decay and converts to 3He which finally interact with neutron to produce tritium. These processes some times defined as Beryllium poison. Negative effect of this process are met whenever beryllium is used in a thermal reactor as a reflector or moderator . Because of their large thermal neutron absorption cross sections , the buildup of He-3 and Li-6 concentrations ,initiated by the Be(n,a) reaction , results in large negative reactivities which alter the reactivity , flux and power distributions. -
Opportunities for Neutrino Physics at the Spallation Neutron Source (SNS)
Opportunities for Neutrino Physics at the Spallation Neutron Source (SNS) Paper submitted for the 2008 Carolina International Symposium on Neutrino Physics Yu Efremenko1,2 and W R Hix2,1 1University of Tennessee, Knoxville TN 37919, USA 2Oak Ridge National Laboratory, Oak Ridge TN 37981, USA E-mail: [email protected] Abstract. In this paper we discuss opportunities for a neutrino program at the Spallation Neutrons Source (SNS) being commissioning at ORNL. Possible investigations can include study of neutrino-nuclear cross sections in the energy rage important for supernova dynamics and neutrino nucleosynthesis, search for neutrino-nucleus coherent scattering, and various tests of the standard model of electro-weak interactions. 1. Introduction It seems that only yesterday we gathered together here at Columbia for the first Carolina Neutrino Symposium on Neutrino Physics. To my great astonishment I realized it was already eight years ago. However by looking back we can see that enormous progress has been achieved in the field of neutrino science since that first meeting. Eight years ago we did not know which region of mixing parameters (SMA. LMA, LOW, Vac) [1] would explain the solar neutrino deficit. We did not know whether this deficit is due to neutrino oscillations or some other even more exotic phenomena, like neutrinos decay [2], or due to the some other effects [3]. Hints of neutrino oscillation of atmospheric neutrinos had not been confirmed in accelerator experiments. Double beta decay collaborations were just starting to think about experiments with sensitive masses of hundreds of kilograms. Eight years ago, very few considered that neutrinos can be used as a tool to study the Earth interior [4] or for non- proliferation [5]. -
Hadron Collider Physics
KEK-PH Lectures and Workshops Hadron Collider Physics Zhen Liu University of Maryland 08/05/2020 Part I: Basics Part II: Advanced Topics Focus Collider Physics is a vast topic, one of the most systematically explored areas in particle physics, concerning many observational aspects in the microscopic world • Focus on important hadron collider concepts and representative examples • Details can be studied later when encounter References: Focus on basic pictures Barger & Philips, Collider Physics Pros: help build intuition Tao Han, TASI lecture, hep-ph/0508097 Tilman Plehn, TASI lecture, 0910.4182 Pros: easy to understand Maxim Perelstein, TASI lecture, 1002.0274 Cons: devils in the details Particle Data Group (PDG) and lots of good lectures (with details) from CTEQ summer schools Zhen Liu Hadron Collider Physics (lecture) KEK 2020 2 Part I: Basics The Large Hadron Collider Lyndon R Evans DOI:10.1098/rsta.2011.0453 Path to discovery 1995 1969 1974 1969 1979 1969 1800-1900 1977 2012 2000 1975 1983 1983 1937 1962 Electric field to accelerate 1897 1956 charged particles Synchrotron radiation 4 Zhen Liu Hadron Collider Physics (lecture) KEK 2020 4 Zhen Liu Hadron Collider Physics (lecture) KEK 2020 5 Why study (hadron) colliders (now)? • Leading tool in probing microscopic structure of nature • history of discovery • Currently running LHC • Great path forward • Precision QFT including strong dynamics and weakly coupled theories • Application to other physics probes • Set-up the basic knowledge to build other subfield of elementary particle physics Zhen Liu Hadron Collider Physics (lecture) KEK 2020 6 Basics: Experiment & Theory Zhen Liu Hadron Collider Physics (lecture) KEK 2020 7 Basics: How to make measurements? Zhen Liu Hadron Collider Physics (lecture) KEK 2020 8 Part I: Basics Basic Parameters Basics: Smashing Protons & Quick Estimates Proton Size ( ) Proton-Proton cross section ( ) Particle Physicists use the unit “Barn”2 1 = 100 The American idiom "couldn't hit the broad side of a barn" refers to someone whose aim is very bad. -
HEPAP Looks Into the Future
Volume 20 Friday, August 29, 1997 Number 17 f INSIDE HEPAP Looks into 2 HEPAP: Voice of the Community the Future 5 Profiles in HEPAP subpanel meets at Fermilab to chart the future of Particle Physics: high-energy physics in the U.S. Dave McGinnis by Donald Sena and Sharon Butler, Office of Public Affairs 6 Barns of Fermilab Charged with recommending how best to In a letter to HEPAP, Martha Krebs, position the U.S. particle physics community Director of the U.S. Department of Energy’s for new facilities beyond CERN’s Large Office of Energy Research, directed the Hadron Collider, a subpanel of the High- subpanel to “recommend a scenario for an Energy Physics Advisory Panel met at Fermilab optimal and balanced U.S. high-energy physics August 14-16 to hear presentations on such program over the next decade,” with “new topics as the research agenda for Fermilab’s facilities to address physics opportunities Run II, the complicated upgrades to the CDF beyond the LHC.” She asked the subpanel and DZero detectors and research on future to consider a future course in light of three accelerators. continued on page 3 Photo by Reidar Hahn Dixon Bogert, deputy project manager for the Main Injector, leads a tour for HEPAP subpanel members and DOE officials. HEPAP: Voice of the Community by Donald Sena and Sharon Butler, Office of Public Affairs The High-Energy Physics Advisory In 1983, for example, a HEPAP According to Fermilab physicist Cathy Panel traces its history to the 1960s, subpanel recommended terminating Newman-Holmes, outgoing member of when -
Searches for a Charged Higgs Boson in ATLAS and Development of Novel Technology for Future Particle Detector Systems
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1222 Searches for a Charged Higgs Boson in ATLAS and Development of Novel Technology for Future Particle Detector Systems DANIEL PELIKAN ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-554-9153-6 UPPSALA urn:nbn:se:uu:diva-242491 2015 Dissertation presented at Uppsala University to be publicly examined in Polhemssalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, Friday, 20 March 2015 at 10:00 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Prof. Dr. Fabrizio Palla (Istituto Nazionale di Fisica Nucleare (INFN) Pisa). Abstract Pelikan, D. 2015. Searches for a Charged Higgs Boson in ATLAS and Development of Novel Technology for Future Particle Detector Systems. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1222. 119 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9153-6. The discovery of a charged Higgs boson (H±) would be a clear indication for physics beyond the Standard Model. This thesis describes searches for charged Higgs bosons with the ATLAS experiment at CERN’s Large Hadron Collider (LHC). The first data collected during the LHC Run 1 is analysed, searching for a light charged Higgs boson (mH±<mtop), which decays predominantly into a tau-lepton and a neutrino. Different final states with one or two leptons (electrons or muons), as well as leptonically or hadronically decaying taus, are studied, and exclusion limits are set. The background arising from misidentified non-prompt electrons and muons was estimated from data. This so-called "Matrix Method'' exploits the difference in the lepton identification between real, prompt, and misidentified or non-prompt electrons and muons. -
Improved Algorithms and Coupled Neutron-Photon Transport For
Submitted to ‘Chinese Physics C’ Improved Algorithms and Coupled Neutron-Photon Transport for Auto-Importance Sampling Method * Xin Wang(王鑫)1,2 Zhen Wu(武祯)3 Rui Qiu(邱睿)1,2;1) Chun-Yan Li(李春艳)3 Man-Chun Liang(梁漫春)1 Hui Zhang(张辉) 1,2 Jun-Li Li(李君利)1,2 Zhi Gang(刚直)4 Hong Xu(徐红)4 1 Department of Engineering Physics, Tsinghua University, Beijing 100084, China 2Key Laboratory of Particle & Radiation Imaging, Ministry of Education, Beijing 100084, China 3 Nuctech Company Limited, Beijing 100084, China 4 State Nuclear Hua Qing (Beijing) Nuclear Power Technology R&D Center Co. Ltd., Beijing 102209, China Abstract: The Auto-Importance Sampling (AIS) method is a Monte Carlo variance reduction technique proposed for deep penetration problems, which can significantly improve computational efficiency without pre-calculations for importance distribution. However, the AIS method is only validated with several simple examples, and cannot be used for coupled neutron-photon transport. This paper presents improved algorithms for the AIS method, including particle transport, fictitious particle creation and adjustment, fictitious surface geometry, random number allocation and calculation of the estimated relative error. These improvements allow the AIS method to be applied to complicated deep penetration problems with complex geometry and multiple materials. A Completely coupled Neutron-Photon Auto-Importance Sampling (CNP-AIS) method is proposed to solve the deep penetration problems of coupled neutron-photon transport using the improved algorithms. The NUREG/CR-6115 PWR benchmark was calculated by using the methods of CNP-AIS, geometry splitting with Russian roulette and analog Monte Carlo, respectively. -
8.1 the Neutron-To-Proton Ratio
M. Pettini: Introduction to Cosmology | Lecture 8 PRIMORDIAL NUCLEOSYNTHESIS Our discussion at the end of the previous lecture concentrated on the rela- tivistic components of the Universe, photons and leptons. Baryons (which are non-relativistic) did not figure because they make a trifling contribu- tion to the energy density. However, from t ∼ 1 s a number of nuclear reactions involving baryons took place. The end result of these reactions was to lock up most of the free neutrons into 4He nuclei and to create trace amounts of D, 3He, 7Li and 7Be. This is Primordial Nucleosynthesis, also referred to as Big Bang Nucleosynthesis (BBN). 8.1 The Neutron-to-Proton Ratio Before neutrino decoupling at around 1 MeV, neutrons and protons are kept in mutual thermal equilibrium through charged-current weak interactions: + n + e ! p +ν ¯e − p + e ! n + νe (8.1) − n ! p + e +ν ¯e While equilibrium persists, the relative number densities of neutrons and protons are given by a Boltzmann factor based on their mass difference: n ∆m c2 1:5 = exp − = exp − (8.2) p eq kT T10 where 10 ∆m = (mn − mp) = 1:29 MeV = 1:5 × 10 K (8.3) 10 and T10 is the temperature in units of 10 K. As discussed in Lecture 7.1.2, this equilibrium will be maintained so long as the timescale for the weak interactions is short compared with the timescale of the cosmic expansion (which increases the mean distance between parti- cles). In 7.2.1 we saw that the ratio of the two rates varies approximately as: Γ T 3 ' : (8.4) H 1:6 × 1010 K 1 This steep dependence on temperature can be appreciated as follows. -
ATLAS Experiment
ATLAS Experiment Control room ATLAS building M. Barnett – February 2008 1 Final piece of ATLAS lowered last Friday (the second small muon wheel) M. Barnett – February 2008 2 M. Barnett – February 2008 3 Still to be done Connecting: Cables, Fibers, Cryogenics M. Barnett – February 2008 4 Celebrations M. Barnett – February 2008 5 News Coverage News media are flooding CERN well in advance of startup "Particle physics is the unbelievable in pursuit of the unimaginable. To pinpoint the smallest fragments of the universe you have to build the biggest machine in the world. To recreate the first millionths of a second of creation you have to focus energy on an awesome scale." The Guardian M. Barnett – February 2008 6 Three full pages in New York Times M. Barnett – February 2008 7 New York Times M. Barnett – February 2008 8 National Geographic Magazine M. Barnett – February 2008 9 National Geographic Magazine M. Barnett – February 2008 10 National Geographic Magazine M. Barnett – February 2008 11 M. Barnett – February 2008 12 M. Barnett – February 2008 13 M. Barnett – February 2008 14 M. Barnett – February 2008 15 M. Barnett – February 2008 16 M. Barnett – February 2008 17 M. Barnett – February 2008 18 M. Barnett – February 2008 19 M. Barnett – February 2008 20 M. Barnett – February 2008 21 M. Barnett – February 2008 22 And on television (shortened version) M. Barnett – February 2008 23 An ATLAS expert explains the Higgs evidence to a layperson. M. Barnett – February 2008 24 US-LHC Student Journalism Program April 2-7, 2008 (overlapping Open Days) Six teams of high school students (3 students/1 teacher) are going to CERN to report on the LHC startup. -
Neutron-Proton Effective Range Parameters and Zero- Energy Shape Dependence
BNL-73899-2005-IR Neutron-proton effective range parameters and zero- energy shape dependence Robert W. Hackenburg June 2005 XXX Physics Department XXX Brookhaven National Laboratory P.O. Box 5000 Upton, NY 11973-5000 www.bnl.gov Managed by Brookhaven Science Associates, LLC for the United States Department of Energy under Contract No. DE-AC02-98CH10886 This is a preprint of a paper intended for publication in a journal or proceedings. Since changes may be made before publication, this preprint is made available with the understanding that it will not be cited or reproduced without the permission of the author. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party’s use or the results of such use of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof or its contractors or subcontractors. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DRAFT Neutron-proton effective range parameters and zero-energy shape dependence R.