2018 ◽  
Vol 7 (2) ◽  
pp. 34 ◽  
Author(s):  
M. K. Marakhtanov ◽  
V. S. Okunev

Abnormally high pressure or temperature can significantly reduce the lifetime of atomic nuclei including stable. A hypothesis on stable nuclei decays caused by mechanical collision of macro-objects containing these nuclei is put forward. Mechanisms of such decays are presented. At the same time the distance between interacting nuclei can be significantly higher than the range of nuclear interaction (as manifestations of strong interaction). In decays initiated by external impact, the mean lifetime with respect to particular decay can change depending on these factors. The hypothesis is verified experimentally. When a bismuth bullet collides with a steel flat target, we see different types of stable bismuth isotope decay including cluster one, which is not found in nature (if there is no external impacts). This new class of physical processes can be related to the collective radioactive decay of atomic nuclei initiated by an external mechanical impact.


2016 ◽  
Vol 87 (2) ◽  
pp. 02B704 ◽  
Author(s):  
S. Axani ◽  
D. Winklehner ◽  
J. Alonso ◽  
J. M. Conrad

2014 ◽  
Vol 2014 ◽  
pp. 1-22 ◽  
Author(s):  
A. Adelmann ◽  
J. Alonso ◽  
W. A. Barletta ◽  
J. M. Conrad ◽  
M. H. Shaevitz ◽  
...  

As we enter the age of precision measurement in neutrino physics, improved flux sources are required. These must have a well defined flavor content with energies in ranges where backgrounds are low and cross-section knowledge is high. Very few sources of neutrinos can meet these requirements. However, pion/muon and isotope decay-at-rest sources qualify. The ideal drivers for decay-at-rest sources are cyclotron accelerators, which are compact and relatively inexpensive. This paper describes a scheme to produce decay-at-rest sources driven by such cyclotrons, developed within the DAEδALUS program. Examples of the value of the high precision beams for pursuing Beyond Standard Model interactions are reviewed. New results on a combined DAEδALUS—Hyper-K search for CP violation that achieve errors on the mixing matrix parameter of 4° to 12° are presented.


1969 ◽  
Vol 19 (9) ◽  
pp. 1127-1152 ◽  
Author(s):  
J. Lipták ◽  
J. Vrzal ◽  
E. P. Grigoriev ◽  
G. S. Katykhin ◽  
J. Urbanec

1980 ◽  
Vol 28 (10) ◽  
pp. 1050-1054 ◽  
Author(s):  
N M Blackett ◽  
D M Parry ◽  
J R Baker

Analysis of autoradiographs at the electron microscope level requires special procedures, since the size of the radioactive structures visualized are comparable to the range of the radioactive decay particles emitted. Quantitative analysis in these circumstances requires that the sizes, shapes, and juxtaposition of the various structures be taken into account in relation to the range distribution of silver grains, produced by the decays, from a point source for the particular isotope and autoradiographic conditions employed. We present the distribution of silver grains about a point source for the four electron capture isotopes 51Cr, 55Fe, 111In, and 125I. Thin radioactive line sources were constructed and the distribution of autoradiographic grains measured. The grain distributions are discussed in relation to the number of particles per disintegration and their energy and range. A simple calculation enables these line source distributions to be converted into point source distributions, which can then be used for whichever method of quantitative analysis is considered appropriate for a particular problem. An outline is given of some of the more important aspects of various methods of analysis.


1965 ◽  
Vol 97 (8) ◽  
pp. 810-816 ◽  
Author(s):  
G. G. Dustan

AbstractLarge numbers of Oriental fruit moth adults were successfully tagged (500 or more counts per minute) by holding them for 24–48 hr. in cages provided with cotton wicks moistened with a water-solution of P32 at 20 microcuries per millilitre. The addition of sugar to the tagging solution did not increase its effectiveness. Approximately 80% of the total radioactivity of the tagged moths was internal due to ingested liquid and the remainder was on the surface of their bodies; 73% of the total was in and on the abdomen. The loss in radioactivity of tagged moths in 1–6 days was 2.2–4.7 times greater than the theoretical loss due to isotope decay alone. The highest rate of loss occurred during the first day, probably through excretion before the P32 was absorbed from the digestive tract. Egg laying contributed to loss of radioactivity. Though water and liquid bait removed some P32 from tagged moths this did not result in appreciable contamination of other moths trapped in the liquids.Attempts to tag large numbers of moths (400–1000 per cage) for release and recovery experiments were only partially successful as the radioactivities attained by individual moths varied widely at different times and from cage to cage, even under the same environmental conditions. This appeared to be partly due to differences in the feeding behaviour of different batches of moths and it may have been influenced by the conditions under which they were reared.


2012 ◽  
Vol 1444 ◽  
Author(s):  
Roberta N. Mulford ◽  
Paul D. Richardson ◽  
Joseph Hickey ◽  
Rene Chavarria

ABSTRACTPlutonium oxide heat sources are used to power space missions. The heat produced by alpha decay of the 238 isotope of Pu is converted to electricity in a thermopile, providing electricity during a substantial fraction of the 88 year half-life of the isotope. Decay of the Pu produces helium and uranium, and a fraction of the evolved helium is captured in the oxide matrix. All of the helium produced in decay can in principle be contained in the oxide lattice, where it occupies the tetrahedral sites. Some helium diffuses out at a rate that is somewhat dependent on the form and morphology of the fuel. Rates have previously been measured for oxide aged about 1 year. Current measurements on sealed heat sources as old as 34 years indicate that the rate of diffusion has changed only slightly over time. Possible mechanisms for helium release include bubble diffusion, point defect migration, agglomeration and movement of He at grain boundaries, and volume diffusion through the lattice sites. We observe primarily diffusion from site to site within the lattice, with an activation energy of 18.7 kcal/mole, independent of point defect movement, despite the rising concentration of helium in the lattice over time and the accumulation of radiation damage within the lattice. Because of the slow diffusion of helium from the fuel to the headspace, heat sources are anticipated to be stable over a long lifetime.


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