scholarly journals The excitation of γ -rays by β -rays

1914 ◽  
Vol 90 (621) ◽  
pp. 521-531 ◽  
Keyword(s):  
Atomic Weight ◽  
Balance Method ◽  
The Other ◽  
Characteristic Radiation ◽  
Definite Evidence ◽  
Radioactive Substances ◽  
Γ Rays ◽  
The Impact ◽  
First Time ◽  
Soft Radiation

The excitation of γ -rays by the impact of β -rays on different substances has been investigated by several observers. The question was first systematically examined by J. A. Gray. He showed that penetrating γ -rays are produced by the β -rays of radium E when they impinge on different materials, the amount of γ -radiation increasing with increase of atomic weight of the material. The particular disposition used in his first experiments was not suitable for the examination of any soft types of radiation which might have been excited, but in later work he showed, for the first time, that characteristic radiations were excited in the case of silver, tin, barium and cerium. Chadwick, using the balance method of Rutherford and Chadwick, examined whether the β -rays from radium B and radium C excite penetrating γ -rays in different kinds of matter. Definite evidence was obtained that an excited radiation amounting to about 0.5 per cent, of the primary γ -radiation is produced. This method, however, was not suitable for the detection of soft characteristic radiations. These general results have recently been confirmed by Starke, using the β -rays from a strong preparation of mesothorium. In previous papers by Rutherford and the author on the analysis of the γ -rays from radioactive substances, it has been shown that the γ -rays emitted by the different products can be separated into groups differing widely in penetrating power. Some of these radiations appear to be characteristic of the elements by which they are emitted and fall into one or other of the series given by Barkla. On the other hand, some of the groups of rays found do not appear to belong to either series. It was further shown in previous work that when radium C is deposited on nickel a soft radiation is given out which is entirely absorbed by 2 mm. of aluminium. This soft radiation was much more readily absorbed than that emitted by radium B, and for which μ = 40 (cm. -1 ), but it was appreciably harder than the characteristic radiation of nickel. Moreover, when radium C was deposited on silver, little, if any, soft radiation appeared to be emitted. It seemed of importance, therefore, to examine in detail the nature of the radiation excited by the β - and γ -rays from radium B and radium C, and to examine the bearing of the results on the type of radiation emitted by different materials on which radium C is deposited.

scholarly journals A place too crowded to study: The impact of student cohort growth on the probability of university dropout

2019 ◽  
Vol 9 (2) ◽  
pp. 189-212
Author(s):  
Andrea Diem ◽  
Stefan C. Wolter
Keyword(s):  
Significant Relationship ◽  
Negative Influence ◽  
The Other ◽  
University System ◽  
Pronounced Increase ◽  
The Us ◽  
University Dropout ◽  
The Impact ◽  
First Time ◽  
Course Of Study

Introduction: This study examines the influence of major fluctuations in the number of students enrolling at university on the probability of dropout or a switch to a different course of study. Findings from the US show that a pronounced increase in student numbers leads to more dropouts. Materials and methods: This article provides an analysis of this relationship for the first time outside the US and for an entire university system. We use administrative data for all the students who started studying at Swiss universities between 1980 and 2001. Results: The results suggest a significant relationship between positive cohort growth and the probability of dropout. A reduction in student numbers, on the other hand, does not increase the probability of persistence. Discussion: Despite the negative influence of a big cohort on the probability of persistence, no statistically significant relationship exists, by contrast, between the change in student numbers and the probability of a student switching to a different course of study.

scholarly journals The absorption in lead of the γ-rays emitted by radium and radium C

1915 ◽  
Vol 91 (630) ◽  
pp. 396-404 ◽  
Keyword(s):  
Atomic Weight ◽  
Great Accuracy ◽  
Complete Analysis ◽  
Characteristic Radiation ◽  
Anomalous Effect ◽  
Γ Radiation ◽  
Additional Information ◽  
Absorbing Material ◽  
Γ Rays ◽  
The Difference

In a previous paper by Rutherford and the author attention has been drawn to the fact that the two types of γ-radiation emitted by radium B and radium c which are exponentially absorbed by aluminium both show irregular absorption curves when lead is used as the absorbing material. The curve obtained for pure radium C was observed to fall far more rapidly than was to be expected only after traversing a thickness of 1·5cm of lead. The absorption curve in lead of the γ-rays from radium B was obtained by taking the difference between the radium (B+C) and the radium C curves. The results so obtained were not determined with very great accuracy, but they served to show that in this case, to, the absorption is not exponential , and that the absorption coefficient rapidly diminished from about μ =11(cm. -1 ) to μ =2(cm -1 ). The accuracy of the curves did not, however, permit of their complete analysis as in the case of those previously obtained for aluminium. During the course of his work on characteristic radiations Barkla has Pointed out and investigated the anomalous effect on the absorption of a characteristic radiation by an element whose atomic weight is near to that of the element which emits the radiation. His experiments were, however, confined to elements of comparatively low atomic weight. As the atomic weights of radium B and radium C can only differ by a small amount, and as they have atomic numbers differing only by unity, viz., radium B=82 and radium C=83, it seemed of importance to determine accurately the absorption curves in lead, and to examine whether any additional information can be obtained which may indicate whether the radiations emitted by radium B and radium C are characteristic of these elements and fall into the series given by Barkla.

scholarly journals Fluorescent röntgen radiation from elements of high atomic weight

1912 ◽  
Vol 86 (589) ◽  
pp. 439-451 ◽  
Keyword(s):  
Scattered Radiation ◽  
Incident Beam ◽  
Smooth Curve ◽  
Atomic Weight ◽  
Primary Beam ◽  
X Rays ◽  
Characteristic Radiation ◽  
X Ray ◽  
Platinum Lead ◽  
Soft Radiation

A considerable amount of work has been done by various experimenters showing that, when an element of higher atomic weight than calcium is subjected to a suitable primary beam of X-rays, the rays which leave the radiator consist of two types: firstly, the purely scattered radiation, which is almost exactly similar to the incident beam, and, secondly, a characteristic homogeneous radiation. The scattered radiation which in the case of a primary beam from an X-ray bulb is heterogeneous, is, with elements of low atomic weight, quite small in intensity when compared with the intensity of the homogeneous radiation which is emitted simultaneously. Owing to this fact, it is comparatively easy to prove that the elements with atomic weights between that of calcium and cerium give off when stimulated with X-rays homogeneous beams, and the hardness of the characteristic radiation from each of these elements has been measured by determining the absorption in aluminium. The radiations are usually defined by the value ok their absorption coefficients, that is, by λ/ρ where I = I 0 e -λx ; ρ = density of aluminium. Using the values obtained, it is possible to plot a curve showing the relation between atomic weight and λ/ρ for the elements which emit a characteristic radiation, taking atomic weight as abscissa and λ/ρ for ordinates. If this is done, it will be found that the elements with atomic weights between that of calcium and cerium lie on an approximately smooth curve (Group K). When, however, the elements with higher atomic weight than silver are examined under suitable conditions, it is found that, with these elements, there are two distinct types of radiations: one, a hard characteristic radiations such as belongs to Group K, and superposed on this a very soft radiation. Prof. Barkla and Mr. Nicol have investigated the soft radiations from the elements silver, antimony, iodine, and barium, and have shown that these elements, in addition to the usual characteristic radiation, emit another very soft radiation, which is also characteristic of the element. The values of the λ/ρ for these elements have been determined, and it has been shown, as far as it is possible with such soft rays, that they are homogeneous. If these values are plotted on the same diagram as that mentioned above, a second short curve is obtained, which can be continued to the X axis; when this is done, if this second curve resembles in shape the curve for Group K, it will pass before it reaches the X axis through the region of atomic weights between 184 and 238. which contains tubgsteb, gold, platinum, lead, bismuth, thorium, and uranium. This second series of elements has been designated Group L. Up to the present it has been impossible to draw this curve with any accuracy, as none of the elements between tungsten and uranium have been investigated as regards their X-ray properties.

scholarly journals Airport Railroad Service Kualanamu Elasticity (Airport Railink Service)

2018 ◽  
Vol 2 (1) ◽  
pp. 22-33
Author(s):  
Mariana Diah Puspitasari ◽  
Dedik Tri Istiantara
Keyword(s):  
Travel Time ◽  
The Other ◽  
Demand Elasticity ◽  
Private Company ◽  
Train Station ◽  
Ticket Price ◽  
International Airport ◽  
Link Service ◽  
The Impact ◽  
First Time

In July 25th, 2013 Indonesia for the first time provided rail link service from and to an airport. It particularly was operated from and to Kualanamu International Airport (KNIA), Deli Serdang, North Sumatera, which was also operated for the first time on that date. Managing the airport rail link service, a private company namely PT. Railink basically is the subsidiary company of PT. Angkasa Pura II (Persero) and PT. Kereta Api Indonesia (Persero). The price of train ticket, in fact, is getting higher as time goes by. It is noted that the ticket price has increased from IDR 80K to IDR 100K since January 15th, 2015. Concerning this situation, this study is conducted to investigate the demand elasticity of the airport rail link service from and to Kualanamu International Airport as well as factors in taking the airport rail link. The result of the study reveals that the demand of airport rail link service as the impact of the increasing of the ticket price is inelastic since its value of elasticity reaches -0.38. The other result, moreover, finds six reasons influencing people to go with airport rail link: comfort, punctuality, speed or travel time, practicality, access to train station, and other modes’ tariff.

scholarly journals The γ-rays from actinium emanation and their origin

1932 ◽  
Vol 136 (829) ◽  
pp. 407-412 ◽  
Keyword(s):  
Fine Structure ◽  
Experimental Evidence ◽  
Long Range ◽  
Strong Evidence ◽  
The Other ◽  
Homogeneous Groups ◽  
Radioactive Substances ◽  
Complex Transformation ◽  
Γ Rays ◽  
The Individual

As a result of recent experiments, evidence is accumulating that the pene­trating γ -rays from radioactive substances have their origin not in the movement of electrons but in the transitions of α -particles in an excited nucleus. Strong evidence in support of this view was obtained by Rutherford, Ward and Lewis from their analysis of the groups of long range α -particles from radium C', and a more detailed discussion of the results was given by Rutherford and Ellis. This problem of the origin of the γ -rays can be attacked in another direction from a consideration of the so-called fine structure shown by the groups of α -particles emitted by certain radioactive substances. In particular, Rosenblum found that the transformation of thorium C was accompanied by the appearance of five homogeneous groups of α -particles. In explanation of these results, Gamow suggested that γ -rays should be emitted as a result of such a complex transformation, the energies of the individual γ -rays corre­sponding to the differences of energies between the α -particles in the various groups. Unfortunately it is a difficult matter to give a decisive answer on this important question. In a recent paper, Ellis concludes that the experimental evidence is in support of Gamow’s theory, but on the other hand, Meitner as a result of her investigations, has expressed a contrary opinion. It is thus of much impor­tance to examine all methods of obtaining evidence on this question.

scholarly journals Bruno Schulz – mistrz, inspirator czy literacki ojciec Jerzego Ficowskiego

2017 ◽  
Vol 16 ◽  
pp. 134-144
Author(s):  
Malwina Wapińska
Keyword(s):  
Paul Ricoeur ◽  
The Other ◽  
Literary Biography ◽  
Harold Bloom ◽  
Other Hand ◽  
Anxiety Of Influence ◽  
Unique Nature ◽  
The Impact ◽  
First Time ◽  
Bruno Schulz

Bruno Schulz – master, inspiration or literary father for Jerzy Ficowski This article explores the artistic relationship between Jerzy Ficowski and Bruno Schulz. For the first time Ficowski came across Schulz’s The Cinnamon Shops in 1942, as a 17 year old adolescent. He remembered that first reading as a moment of epiphany which occurred to be crucial to the whole further Ficowski’s literary biography. The young poet hailed the author of The Cinnamon Shops as his great master, the only one who dared to express the true importance of myth to the artistic imagination in such an unique way. The influence of Schulz’s prose on Ficowski’s poetry was unquestionable. However, this does not mean that Ficowski’s work was secondary to Schulz’s or less original. Jerzy Ficowski, like Schulz, emphasized the importance of childhood and myth in a poet’s imagination. On the other hand, both writers found themselves different ways to express those ideas in artistic way. To analyze the unique nature of artistic relationship between Bruno Schulz and Jerzy Ficowski, I refer to the famous Harold Bloom’s work The Anxiety of Influence. A theory of Poetry.Key words: Jerzy Ficowski; Bruno Schulz; biography; interpretation; fictionalisation; the impact of poetic; Paul Ricoeur; Harold Bloom; psychoanalysis;

Analysis of the dynamic response of a fluid-supported circular elastic plate impacted by a low-velocity projectile

2000 ◽  
Vol 214 (5) ◽  
pp. 719-727 ◽  
Author(s):  
W Huang ◽  
Y Li ◽  
W Chen
Keyword(s):  
Dynamic Response ◽  
Elastic Plate ◽  
Impact Force ◽  
The Other ◽  
Sound Waves ◽  
Low Velocity ◽  
The Impact ◽  
First Time ◽  
Transverse Deflection ◽  
Clamped Edges

In this paper, the dynamic response of a thin circular elastic plate supported by a fluid on one side and impacted by a low-velocity projectile on the other side is analysed for the first time. A semi-analytical method is put forward, a non-linear Volterra integral equation governing the impact force is deduced and a linear numerical method is used to solve the equation and calculate the transverse deflection of the plate. The presence of the fluid not only lowers, on account of increased inertia, the natural frequency of the plate vibrating in vacuum but also dampens its transverse vibration owing to the energy carried off in the form of sound waves. As a numerical example, the transverse deflection of a solid circular plate with clamped edges impacted centrally by a low-velocity sphere and the impact force are computed, and the results are discussed.

scholarly journals Minimizing tourist impact on the Argentine Islands ecosystem, Antarctic Peninsula, using visitor site guidelines approach

2021 ◽  
pp. 98-116
Author(s):  
H. Yevchun ◽  
◽  
E. Dykyi ◽  
I. Kozeretska ◽  
A. Fedchuk ◽  
...  
Keyword(s):  
Environmental Impact ◽  
The Other ◽  
Deschampsia Antarctica ◽  
Central Values ◽  
Antarctic Research ◽  
Key Features ◽  
Critical Requirement ◽  
The Antarctic ◽  
The Impact ◽  
First Time

There has been an ongoing increase in tourist visits to the Antarctic since 2010. These visits primarily concentrate on a small number of sites, increasing the possible environmental impact. One of the tourism hotspots is the central Argentine Islands in Wilhelm Archipelago. These islands, being one of the top 20 most visited Antarctic sites, consist of Galindez Island, Winter Island, and Skua Island. They are known for wildlife, rich vegetation (old moss banks, rich bryophyte and lichen communities, Antarctic pearlwort Colobanthus quitensis and hairgrass Deschampsia antarctica populations), spectacular views. They include one of the oldest Antarctic research stations: the Ukrainian Antarctic Akademik Vernadsky station. Previously no measures have been developed to minimize the impact of tourism on this region. Thus, the Visitor Site Guidelines (VSG) approach and the numerous studies in the region were used to determine the central values of this site and to identify those key features that can be opened for tourists. In addition to the most frequently mentioned values, such as seabirds and mammals, we considered it necessary to mention the vegetation. We assessed threats to these values, distinguishing known and potential impacts. We have also analyzed and developed landing requirements for the studied area, including the most critical requirement to be considered, namely the number of visitors. We think that the maximum number of visitors should be 36 at any time and 270 per day, not counting passengers of yachts. This is the first time that the Visitor Site Guidelines were modified to limit the number of yachts visiting the site to three yachts per day. To reduce the tourist load at the station itself and at the same time to concentrate tourists in the studied region, we proposed two tourist trails: one for Galindez Island, the other — the existing trail for Winter Island. The prepared draft of Visitor Site Guidelines is given in Appendix 2.

scholarly journals Redshifted 21-cm bispectrum – II. Impact of the spin temperature fluctuations and redshift space distortions on the signal from the Cosmic Dawn

2021 ◽  
Vol 502 (3) ◽  
pp. 3800-3813
Author(s):  
Mohd Kamran ◽  
Raghunath Ghara ◽  
Suman Majumdar ◽  
Rajesh Mondal ◽  
Garrelt Mellema ◽  
...  
Keyword(s):  
Temperature Fluctuations ◽  
Source Model ◽  
The Other ◽  
Spin Temperature ◽  
Sign Reversal ◽  
X Ray ◽  
Simulated Signal ◽  
Source Models ◽  
The Impact ◽  
First Time

ABSTRACT We present a study of the 21-cm signal bispectrum (which quantifies the non-Gaussianity in the signal) from the Cosmic Dawn (CD). For our analysis, we have simulated the 21-cm signal using radiative transfer code grizzly, while considering two types of sources (mini-QSOs and HMXBs) for Ly α coupling and the X-ray heating of the IGM. Using this simulated signal, we have, for the first time, estimated the CD 21-cm bispectra for all unique k-triangles and for a range of k modes. We observe that the redshift evolution of the bispectrum magnitude and sign follow a generic trend for both source models. However, the redshifts at which the bispectrum magnitude reaches their maximum and minimum values and show their sign reversal depends on the source model. When the Ly α coupling and the X-ray heating of the IGM occur simultaneously, we observe two consecutive sign reversals in the bispectra for small k-triangles (irrespective of the source models). One arising at the beginning of the IGM heating and the other at the end of Ly α-coupling saturation. This feature can be used in principle to constrain the CD history and/or to identify the specific CD scenarios. We also quantify the impact of the spin temperature (TS) fluctuations on the bispectra. We find that TS fluctuations have maximum impact on the bispectrum magnitude for small k-triangles and at the stage when Ly α coupling reaches saturation. Furthermore, we are also the first to quantify the impact of redshift space distortions (RSD), on the CD bispectra. We find that the impact of RSD on the CD 21-cm bispectra is significant ($\gt 20{{\ \rm per\ cent}}$) and the level depends on the stages of the CD and the k-triangles for which the bispectra are being estimated.

scholarly journals Effect of positive and negative interface trap charges on the performance of M-FinFET and its RF/linearity analysis

2021 ◽  
Author(s):  
Rinku Rani Das ◽  
Atanu Chowdhury ◽  
Apurba Chakroborty ◽  
Santanu Maity
Keyword(s):  
Semiconductor Device ◽  
Cmos Technology ◽  
The Other ◽  
Interface Trap ◽  
Trap Concentration ◽  
Device Efficiency ◽  
The Impact ◽  
First Time ◽  
Intrinsic Gain ◽  
Trap Charges

Abstract Multiple Fins structured FinFET (M-FinFET) is a promising semiconductor device for future improvisation of CMOS technology. In this paper, we investigate the impact of interface trap charges (positive and negative trap) at the HfO2/Si interface in M-FinFET for the first time. The various important DC attributes, RF/analog, and linearity metrics are studied in presence and absence of traps. Simultaneously, the various trap concentration effect on the characteristics of M-FinFET are also observed. The results show that the introduction of interface trap charges (ITC) has optimized the ON current, OFF current, and also improves sub-threshold swing (SS) characteristics as compared to no trap condition. It is observed that positive trap having trap concentration of 1012/cm2 enhances the ION ~5.14x, SS by 44.75%, and various important RF/analog parameter such as transconductance (Gm) improves by a factor 5, device efficiency by 7.4% and intrinsic gain (Av) 80.4%. On the other hand, linearity parameters like VIP2, VIP3 and 1 dB compression point show better performance in presence of positive and negative trap.

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