Areas Of Experimental Physics Research Articles

Razors and lasers: an undergraduate experiment to determine thermal expansion coefficients using single slit diffraction measurements

Single slit diffraction and the thermal expansion of materials are common components of an undergraduate physics course, though these topics are often taught independently in both lectures and laboratory based courses. Higher levels of cognitive domains can be achieved by building on these established topics and combining them into a single experiment that also introduces new tools and techniques for data handling and analysis. Here we describe an experiment where the thermal expansion of a metal bar shifts an attached razor blade such that the separation between this blade and another fixed blade decreases. This decrease in blade separation allows for changes in the peak separation for single slit diffraction to be measured and the expansion coefficient of three metal bars (copper, steel and aluminium) is determined to good agreement with accepted values. The use of multiple peak fitting allows students to develop more sophisticated analysis techniques that are applicable beyond this experiment and are transferable to different areas of experimental physics.

Thin carbon foil resistance to differential pressure

Thin carbon foils are used in different environments for various purposes. For example, they are used in vacuum technology to create a barrier between two volumes, in space plasma instrumentation to detect the crossing of a particle passing through them, or as a stripper of electrons for high energy particles. In the case of a change of pressure on either side of the foil, the pressure differential creates mechanical stresses to the foil that can lead to irreversible damage. Few experiments have characterized the survivability of carbon foils as a function of pressure. In this study, we show measurements of the resistance to pressure of carbon foils (CF) up to partial rupture. The focus is on ultra-thin carbon foils (e.g., 0.5–1.0 μg/cm2) that are typically used in space plasma instrumentation. However, our results can be used in other areas of experimental physics. Our results show that the finer the pitch of the supporting grid, the more pressure resistant the foil is, indicating that the CF support grid is perhaps more important in the design trade than the foil thickness. For example, we find that nominal 1.0 μg/cm2 foils mounted on 13.1 lpmm (333 lines per inch) nickel grids can hold a remarkable static pressure of ∼9 kPa (∼1.3 psi) with almost no damage.

From Darwin and Wallace to the discovery of Invar

Charles Darwin conceived his theory of the origin of species by natural selection following his voyage as naturalist on HMS Beagle . Among the many things he observed and pondered upon was the fact that in the Galapagos islands most of the animal species were found nowhere else in the world, and

Very Long Baseline Neutrino Oscillation Experiments for Precise Measurements of Mixing Parameters and CP Violating Effects

Recent exciting results have shown that neutrinos oscillate between their weak eigenstates and thus must not only be massive but their mass and flavor eigenstates do no coincide. This has opened a whole new area of experimental physics where one strives to precisely measure the mixing parameters, search for potential CP symmetry violation in the lepton sector and understand secondary effects, such as how the oscillations are affected when the neutrinos pass through matter. It is possible to measure all of the oscillation parameters in a single experiment by employing a 1-MW wide-band neutrino super-beam, a very long baseline of ∼2500 km and a 500-kton massive far detector.

A VME RISC processor farm for third level triggering

The need for very fast, compact, VME-based farms of processors exists in many areas of experimental physics. Reported is a development for such a farm targeted at the requirements of the online and trigger system of the CERN experiment PS195 (CPLEAR). The system is characterized as being VME based and requiring small events (around 1 kbyte) to be processed at a high rate (greater than 1 kHz). The development was for a single chassis system, using the MIPS R3000 chip mounted on a commercially available board. >

Concepts of Space by Max Jammer

554 BOOK REVIEWS The author's principal aim in the book, to return to this for emphasis, is " to elucidate the aims which the critics themselves profess." Professor Osborne does not believe that it lies within the province of criticism to justify these aims and assumptions, although this belief does not prevent his making a certain number of critical evaluations about various features of the different assumptions. I should like to repeat that within the limits the author lays down, he admirably succeeds, by and large. There is a wealth of information and comment in the book and a rich acquaintance with what artists and critics have said and held. Presumably the author thinks that the more definitive and positive evaluation of assumptions in criticism belongs to aesthetics rather than to criticism, a separation that he may press too absolutely. Nevertheless, the author makes it clear that the task of aesthetics and philosophy of art is important and needs to be done. What he has well done here is to show how criticism is significant and intelligent when it proceeds consistently from original assumptions. Since relatively few critics are successful in this respect, Mr. Osborne's book is valuable and useful for aiding critics to write intelligibly. The larger and more basic issue of aesthetics itself can then be faced more successfully. University of Notre Dame Notre Dame, Indiana. JOHN A. OESTERLE Concepts of Space. By MAX JAMMER. Cambridge: Harvard University Press, 1954. Pp. 212 with index. $3.75. One of the major problems occupying the attention of modern Philosophy, particularly that of American Philosophy, is that of integrating the results of modem empiriological disciplines with a knowledge of the underlying natures of things. This problem is especially difficult in the area of experimental Physics. The other phenomenal sciences retain a solid anchor in the natural principles of human knowledge, but experimental Physics is a strange discipline in which proficiency depends on an ascetic renunciation of the normal tendencies of the mind. It is possible, of course, to overstate the problem, and to insist that natural philosophy be so altered that it is deduced from experimental Physics, or at least that it assimilate the physicists' conclusions without change. An analysis or the principles and IDf '.1ods reveals experimental Physics as more of a conceptual substitute k ~ality than a.'l immaterial assimilation, more art than science. But Physics is such a successful art that it set ns absurd to suppose that this conceptual framework is a purely arbitrary construction. If we can BOOK REVIEWS 555 manage qualitative data by treating them as though they were essentially species of quantity, we must suspect, at least, that the two are so closely related that their interdependence is not adequately expressed by the usual insistence on locomotion as the basic type of motion and on quantity as the first material accident, the foundation of the sensible qualities. A discerning comparison of the philosophic notion of place and the physicist. conception of space certainly seems one approach to the problem in consideration of the basic part these two ideas play in the different accounts given of local motion. Yet oddly enough there are few enough works that undertake such a task on more than a textbook level. Max Jammer's book, Concepts of Space, may not unravel the enigma of the relation between the philosophical and the empiriological views on these issues, but at least it is a step in the right direction. Dr. Jammer lectures on Physics and on the history of science at the Hebrew University in Jerusalem. On the evidence of this book, he seems much more sensitive to man's achievement in the realms of theology and philosophy than is usually the case with most historians of science. This book, Concepts of Space, Dr. Jammer wrote while Visiting Lecturer at Harvard University. The contents of the book are well described by the subtitle, " The History of Theories of Space in Physics." The story begins with the concepts of place and space in ancient Greek Philosophy, with the major emphasis on Aristotle and his influence. Some reference is made to the presence within Greek culture of a method of studying reality...