The muon is one of the first elementary particles discovered. It is also known as heavy electron, and it's the main component of cosmic rays flux at sea level. Its flow is continuous, 24h/7d, and it is free. It is natural and does not have any radio protection banning or limitation to its use in schools and can be managed safely by the students. AMELIE is a light, small and didactic apparatus to measure the lifetime of the muons. It is useful tool to introduce the modern physics, particle physics, particles instability and decay, special relativity etc. It can be used for small didactic but complete experiments for measurement of muon rate and lifetime, correction and equalization of data collected etc. A useful instrument to introduce and teach the scientific method to the students. Last but not least, do not contain any dangerous system like high voltage or explosive gas and the cost is relatively cheap.
We measured signals of low amplitudes originating from cosmic rays, using two rectangular-block scintillation detectors at various positions. The signals were analyzed by a slightly modified signal analyzer from project 'MuonLab', designed to measure the lifetime and velocity of muons from cosmic radiation in high school education. In our experiment we focused on the possibilities of the apparatus to measure the time difference 'deltatime (DT)' between signals in two scintillation detectors and the signal amplitude 'pulse height (PH)' of the signal in one detector. We performed measurements in two arrangements: first vertical, detectors parallel and above each other, second horizontal, detectors parallel and next to each other. We observed that in both the vertical and horizontal arrangements, low-amplitude signals from cosmic rays in the two detectors showed unexpected coincidences. Under normal experimental conditions these effects were not observed because the amplification in the photomultiplier (PMT) as well as the threshold voltage were intentionally chosen to avoid noise and excessively high count rates. The rate at which the coincidences occur is very small, more than a thousand times smaller than the count rates of the individual detectors. However, the measurement of the deltatime spectrum appears to be a sensitive way to detect the presence of these rare and unexpected effects. The time differences between the signals at the two analyzer inputs were measured with a resolution of 0.5 ns and the pulse height measurement had a resolution of approximately 8 mV. It is estimated that the low-amplitude signals involved in the coincidences must respond to energy absorptions of the order of 100 keV in the scintillator material.
A treatment is given of the precession of a Foucault pendulum by means of two successive rotational transformations of coordinate system. The simplicity and accuracy of this approach is emphasized.
Daryl Joe D. Santos, Tomotsugu Goto, Ting-Yi Lu
et al.
As recent advancements in physics and astronomy rapidly rewrite textbooks, there is a growing need in keeping abreast of the latest knowledge in these fields. Reading preprints is one of the effective ways to do this. By having journal clubs where people can read and discuss journals together, the benefits of reading journals become more prevalent. We present an investigative study of understanding the factors that affect the success of preprint journal clubs in astronomy, more commonly known as Astro-ph/Astro-Coffee (hereafter called AC). A survey was disseminated to understand how institutions from different countries implement AC. We interviewed 9 survey respondents and from their responses we identified four important factors that make AC successful: commitment (how the organizer and attendees participate in AC), environment (how conducive and comfortable AC is conducted), content (the discussed topics in AC and how they are presented), and objective (the main goal/s of conducting AC). We also present the format of our AC, an elective class which was evaluated during the Spring Semester 2020 (March 2020 - June 2020). Our evaluation with the attendees showed that enrollees (those who are enrolled and are required to present papers regularly) tend to be more committed in attending compared to audiences (those who are not enrolled and are not required to present papers regularly). In addition, participants tend to find papers outside their research field harder to read. Finally, we showed an improvement in the weekly number of papers read after attending AC of those who present papers regularly, and a high satisfaction rating of our AC. We summarize the areas of improvement in our AC implementation, and we encourage other institutions to evaluate their own AC in accordance with the four aforementioned factors to assess the effectiveness of their AC in reaching their goals.
Studies on physics identity have shown that it is one of the main factors that can predict a person's persistence in the field; therefore, studying physics identity is critical to increase diversity within the field of physics and to understand what changes can allow more women and minorities to identify with the field. In this study, we investigate informal physics programs as spaces for physics identity exploration. These programs provide unique conditions under which to study physics identity development along with other identities. Informal physics spaces allow for voluntary engagement, as well as elements of agency and autonomy within the exploration of physics. Thus these spaces allow an identity to form outside of the constraints traditionally found in academic settings. In this work, we operationalized the Community of Practice (CoP) framework to study the development of physics identities within university students who facilitate informal physics programs. We present the stories from two physics graduate students out of our sample to provide a context for testing the feasibility of the extended framework and to identify how experiences within an informal physics program can shape physics identity development. This paper presents the operationalized constructs within the Community of Practice framework, how these constructs are applied to the narrated experiences of our participants, and highlights how we can use this framework to understand the nuances of physics identity development as well as the factors that can influence that development.
In the aforementioned paper, the authors claim that my results concerning the consequent application of Garrett's method for obtaining approximate expressions of the bound states energy of a particle in a finite rectangular well are incorrect. I shall show hat this is not the case, and demonstrate that both their and my results lead to the same conclusion, i.e. that the consequent application of Garrett's method is equivalent to Barker's approximation.
GrayStar is a stellar atmospheric and spectral line modelling, post-processing, and visualisation code, suitable for classroom demonstrations and laboratory-style assignments, that has been developed in Java and deployed in JavaScript and HTML. The only software needed to compute models and post-processed observables, and to visualise the resulting atmospheric structure and observables, is a common Web browser. Therefore, the code will run on any common PC or related X86 (-64) computer of the type that typically serves classroom data projectors, is found in undergraduate computer laboratories, or that students themselves own, including those with highly portable form-factors such as net-books and tablets. The user requires no experience with compiling source code, reading data files, or using plotting packages. More advanced students can view the JavaScript source code using the developer tools provided by common Web browsers. The code is based on the approximate gray atmospheric solution and runs quickly enough on current common PCs to provide near-instantaneous results, allowing for real time exploration of parameter space. I describe the computational strategy and methodology as necessitated by Java and JavaScript. In an accompanying paper, I describe the user interface and its inputs and outputs and suggest specific pedagogical applications and projects. I have made the application itself, and the HTML, CSS, JavaScript, and Java source files available to the community. The Web application and source files may be found at www.ap.smu.ca/~ishort/GrayStar.
The present technical notes offer a brief summary of the essential points of electromagnetism at the undergraduate physics level. Some problems are presented at the end of each section; those with solutions are marked with an asterisk.
A very low-cost, easy-to-make stopwatch is presented to support various experiments in mechanics. The high-resolution stopwatch is based on two photodetectors connected directly to the microphone input of the sound card. A dedicated free open-source software has been developed and made available to download. The efficiency is demonstrated by a free fall experiment.
Marcella [arXiv:quant-ph/0703126] has presented a straightforward technique employing the Dirac formalism to calculate single- and double-slit interference patterns. He claims that no reference is made to classical optics or scattering theory and that his method therefore provides a purely quantum mechanical description of these experiments. He also presents his calculation as if no approximations are employed. We show that he implicitly makes the same approximations found in classical treatments of interference and that no new physics has been introduced. At the same time, some of the quantum mechanical arguments Marcella gives are, at best, misleading.
The magnitude of the angular momentum ($J^2$) in quantum mechanics is larger than expected from a classical model. We explain this deviation in terms of quantum fluctuations. A standard quantum mechanical calculation gives the correct interpretation of the components of the angular momentum in the vector model in terms of projections and fluctuations. We show that the addition of angular momentum in quantum mechanics gives results consistent with the classical intuition in this vector model.
Ettore Majorana was a member of Enrico Fermi's research group in Rome, Italy. Fermi did regard Majorana as much brihter than himself as far as theoretical physics was concerned (more information can be found particularly in the arXives' e-print physics/9810023, in Italian, and refs therein, and also in the recent multilanguage arXiv:0708.2855v1 [physics.hist-ph]). In 1937 Majorana partecipated in the national Italian competition, for a chair in theoretical phyics, requested by Emilio Segre' at that time at Palermo University: Other competitors being GC.Wick, G.Racah, and G.Gentile jr. After a proposal of the judging Commette, chaired by E.Fermi, Majorana got a full-professorship at Naples University, for exceptional scientific merits, outside the competition normal procedures. In this e-print we make known the notes prepared by Majorana for his Inaugural Lecture (and discovered long ago, in 1973, by one of the present editors (ER)),together with some comments of ours: everything being both in English (first article) and in Italian (second article, with a short Bibliography at its end). The present articles have been prepared on the occasion of the Centenary (2006) of Majorana's birth. The preliminary notes for his Inaugural Lecture reveal Majorana's interest not only for scientific research, but also for the best didactical methods to be followed in order to teach classical and quantum physics in the most effective way (while his approach to Special Relativity is known to us from his lecture notes, published elesewhere). P.S.: Il Riassunto in Italiano appare all'inizio della versione italiana.
In this article we are willing to give some first steps to quantum mechanics and a motivation of quantum mechanics and its interpretation for undergraduate students not from physics. After a short historical review in the development we discuss philosophical, physical and mathematical interpretation. We define local realism, locality and hidden variable theory which ends up in the EPR paradox, a place where questions on completeness and reality comes into play. The fundamental result of the last century was maybe Bell's that states that local realism is false if quantum mechanics is true. From this fact we can obtain the so called Bell inequalities. After a didactic example of the fact what these inequalities means we describe the key concept of quantum entanglement motivated here by quantum information theory. Also classical entropy and von Neuman entropy is discussed.
This is a written version of a series of lectures aimed at undergraduate students in astrophysics/particle theory/particle experiment. We summarize the important progress made in recent years towards understanding high energy astrophysical processes and we survey the state of the art regarding the concordance model of cosmology.
Newton's second law may be used to obtain a wave equation, which reduces to Schrodinger's equation in the nonrelativistic limit and for a conservative force.
A refinement of an argument due to Maxwell for the equipartition of kinetic energy in a mixture of ideal gases with different masses is proposed. The argument is elementary, yet it may work as an illustration of the role of symmetry and independence postulates in kinetic theory.
We recall the origins of differential calculus from a modern perspective. This lecture should be a victory song, but the pain makes it to sound more as an oath for vendetta, coming from Syracuse two milenia before.
Eleonora Alfinito, Rosario G. Viglione, Giuseppe Vitiello
The decoherence mechanism signals the limits beyond which the system dynamics approaches the classical behavior. We show that in some cases decoherence may also signal the limits beyond which the system dynamics has to be described by quantum field theory, rather than by quantum mechanics.