Experiments in Particle Physics in the Twentieth Century
Publication Year: 2013
Published by: University of Pittsburgh Press
Title Page, Copyright
In his one-paragraph short story “On Exactitude in Science,” the great Argentinian writer Jorge Luis Borges presents a literary forgery, where the following quotation is fictitiously attributed to Suárez Miranda: “. . . In that Empire, the Art of Cartography attained such Perfection that the map of a single Province occupied the entirety of a City, and the map of the ...
Prologue: The Rise of the Sigmas
Before beginning the discussion about changes in the experimental practices of particle physics in the twentieth century, it is worthwhile to introduce readers to changes in the field’s most notable experimental standard, namely, its use of standard deviation to measure the accuracy and credibility of results....
The history of the changing standards for scientific discovery in particle physics discussed in the prologue suggests that it might be interesting to investigate whether other aspects of experiment and the reporting of experimental results in that field have changed with time. If we look at the history of the use of statistics, we find considerable additional change....
Chapter 1 “Some Measurements of the Temperature Variation in the Electrical Resistance of a Sample of Copper"
The purpose of this experiment was stated clearly in the first lines of the paper: “Precision in the determination of the temperature variation of resistance in copper is important not only to electrical science, but also to its applications. Our estimate of the temperature of remote or inaccessible positions, as, for example, the ocean bed on which a submarine cable lies...
Chapter 2 “Do Falling Bodies Move South?”
Edwin Hall, well-known for the discovery of the effect that bears his name,1 devoted two papers to a discussion of the question of whether falling bodies move south. The first paper, entirely devoted to the history of the subject, began with an admission that it was not an important scientific question.2 Hall’s commentary, however, on previous experiments...
Chapter 3 “The Isolation of an Ion, a Precision Measurement of Its Charge, and the Correction of Stokes’s Law”
Robert Millikan’s experiments on oil drops (Millikan 1911, 1913) are justly regarded as significant contributions to twentieth-century physics. They established the quantization of electric charge, the existence of a fundamental unit of charge, and they measured that fundamental unit more precisely than had been done previously.1 Although Millikan’s 1913 paper...
Chapter 4 “Directed Quanta of Scattered X-rays”
In 1923 Arthur Compton (1923) calculated, using Einstein’s quantum (photon) theory of electromagnetic radiation (Energy = hv, momentum = hv/c, where h is Planck’s constant, v is the frequency of the radiation, and c is the speed of light) and relativistic kinematics, that, in the scattering of electromagnetic radiation from electrons, “the energy in the scattered...
Chapter 5 “A Determination of e/m for an Electron by a New Deflection Method”
Dunnington (1933) reported on a new deflection method of measuring e/m, the charge to mass ratio of the electron. At the time there was a discrepancy between the values found for e/m by different methods; the deflection method, in which the electrons were deflected by magnetic or electric fields, and the spectroscopic method, which used the measurement ...
Chapter 6 An Uncertain Interlude
Dunnington’s (1933) caution in assigning an experimental uncertainty to his measured value of e/m was no doubt influenced by the fact that the value of this quantity previously obtained by different methods differed by far more than the stated experimental uncertainties. Using the ratio of external ...
Chapter 7 “Electron Polarization”
Shull, Chase, and Myers’s (1943) experiment was designed not only to demonstrate the existence of free electron polarization (electrons with more spins pointing in one direction than in the opposite direction) but also to compare the result with theoretical predictions on electron scattering...
Chapter 8 “Mean Lifetime of V-Particles and Heavy Mesons”
Alford and Leighton (1953) dealt with the then recently discovered Vparticles, so named because they were neutral particles that decayed into two charged particles, giving rise to what looked like a “V” in a cloud chamber photograph (figure 8.1).1 These particles had been discovered by Rochester and Butler (1947). By the time of the Alford and Leighton paper, the experimental group at Caltech had already published a preliminary ...
Chapter 9 “Detection of the Free Antineutrino”
Before focusing on Reines et al. (1960), it is important to understand that in 1958 things changed. From its initial publication in 1893, Physical Review had included a “Minor Contributions” section. This had contained book reviews and minutes of meetings of the American Physical Society, which included brief summaries of papers presented at those meetings. In 1929 ...
Chapter 10 “Measurement of the Ke2 Branching Ratio”
In Bowen et al. (1967) the analysis of the data was an exercise in selectivity.1 There was a large experimental background that masked or mimicked the desired signal. It was so large that the signal for the phenomenon under investigation could not initially be seen in the data. In order to isolate that signal, various selection criteria, or cuts, had to be applied to the data so ...
Chapter 11 “Determination of K /3 Form Factors from Measurements of Decay Correlations and Muon Polarizations”
Merlan et al.’s (1974) experiment was also devoted to investigating the decays of the K meson, in particular the Kl3 decays (K → l π0 ν), where l can be either an electron or a muon. Although there are some similarities to the techniques used in the Ke2 experiment discussed in the previous...
Chapter 12 Bad Data An Interlude
In the previous two chapters we have seen examples of experiments in which the application of selection criteria was absolutely essential to the production of an experimental result. We might contrast this with the exclusion of data, which we saw in earlier experiments. Thus, for example, Kennelly and Fessenden (1894) excluded data because they were not...
Chapter 13 “Measurement of the Antineutron-Proton Cross Section at Low Energy”
The purpose of Gunderson et al.’s (1981)1 experiment was to investigate the nucleon-antinucleon interaction at low energy to see if there were resonances or bound states near threshold, which was, at the time, an open question: “A strong motivation for the study of the N̄-N [nucleon-antinucleon] cross section at low energy is the possible existence of resonance ...
Chapter 14 “New Measurements of Properties of the Ω− Hyperon”
In 1964 Barnes et al. (1964) reported the observation of a hyperon with strangeness minus three, the Ω− particle.1 The existence of this particle, and its mass, had been predicted theoretically and, as the experimenters remarked, “consequently, the existence of the Ω− has been cited as a crucial test of the theory of unitary symmetry of strong interactions. The mass is...
Chapter 15 The Coherent Scattering of Neutrinos
Weber’s (1988) paper is included here because the consensus of the physics community is that the experimental result reported is wrong.1 It is, however, interesting to compare the structure of Weber’s paper with that of the papers that attempted to replicate his results and failed to do so. The latter experiments were, and are, regarded as showing that Weber’s results...
Chapter 16 “Search for Neutral Weakly Interacting Massive Particlesin the Fermilab Tevatron Wideband Neutrino Beam”
Gallas et al.’s (1995) experiment was designed to look for neutral weakly interacting massive particles (WIMPs). The use of “Search for” in the title usually, but not always, indicates that the experiment found no evidence for the existence of the sought after phenomenon.1 The experimenters noted that the time-of-flight technique to search for such particles had ...
Chapter 17 “Measurement of the B Total Cross Section and B Differential Cross Section dσ/dpT in pp̄ Collisionsat √s = 1.8 TeV”
Acosta et al.’s (2002) experiment, the second of two performed on the same subject by the Collider Detector at Fermilab (CDF) group, was designed to check on previous results and to test the predictions of quantum chromodynamics (QCD). The experimenters noted that they needed to show that the theoretical predictions provided an adequate description...
Chapter 18 “B Meson Decays to Charmless Meson Pairs Containingη or η’ Mesons”
Aubert et al. (2009) was an experiment that used a more recent set of measurements, specifically a larger data sample, than those experiments done previously by the BaBar group, and it was also a test of the theoretical Standard Model and its extensions. The group measured various branching ratios, the fraction of all B meson decays into a particular decay...
Chapter 19 The Case of the Disappearing Sigmas
In the prologue I discussed the idea that the use of the five-sigma criterion required both knowledge and judgment and was not merely the application of a formula to the data. In this chapter I present a case study that illustrates this. In 2003 the CLAS Collaboration at the Jefferson Physical Laboratory published a paper titled “Observation of an...
It is clear that there have been significant changes in both experiments and in the reporting of experimental results during the twentieth century. I caution, however, that any conclusions drawn apply only to experiments on elementary particles and their properties and to experiments in ...
Page Count: 352
Publication Year: 2013
OCLC Number: 870684378
MUSE Marc Record: Download for Shifting Standards