[Triumf-seminars] TRIUMF Nuclear Physics Seminar today at 11:00

[TRIUMF Seminars]

Date/Time: Fri 2023-09-15 at 11:00

Location:  Auditorium/Hybrid   

Speaker:   John Lestone (Los Alamos National Laboratory)

Title:     Ruhlig's 1938 observation of the fusion of A=3 ions with deuterium-  An analysis of secondary reactions following dd fusion in a heavy phosphoric target

Abstract: Join Zoom Meeting
https://uvic.zoom.us/j/89942968471?pwd=RmJBUkRqNzlVV21IaUYyQmFhTngwdz09

Meeting ID: 899 4296 8471
Password: 136590
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While studying d(d,n)3He fusion in 1938, Ruhlig observed protons with energies larger than 15 MeV, perhaps recoiling from a cellophane foil. This led Ruhlig to hypothesize he was observing secondary (in flight) t + d fusions and conclude that the d(t,n) reaction "must be an exceedingly probable one." This was the first attempt to quantify the probability of d(t,n) fusion, using the 1-MeV tritons generated by d(d,p)t fusion. This caused some Manhattan-project scientists to suggest that the d(t,n) cross sections are significantly higher than those for deuteron-on-deuterium fusion, and led to the first measurement of d(3He,p) and d(t,n) cross sections in 1943. 
We have used modern cross sections and stopping powers to estimate the expected numbers of high-energy protons associated with in-flight t(d,n) reactions in Ruhlig's experiment. Our estimate is four orders of magnitude lower than Ruhlig's observed rate. The number of high-energy protons in Ruhlig's experiment can be obtained via simulation if the protons are assumed to have been emitted by secondary in-flight 3He(d,p) reactions, with various plausible assumptions about the experimental geometry and target-backing thickness. Yet another possibility is that stopped tritons bred in the target by d(d,p)t reactions, in an earlier experiment or perhaps during the same experiment, underwent d(t,n) fusion reactions induced by beam deuterons (this scenario is hard to quantify owing to a lack of experimental details available).
Our calculations demonstrate that quantitative information about the fusion of A=3 ions with deuterium could have been obtained via experiments similar to Ruhlig's well in advance of the advent of 3He-ion and triton beams in 1943. This opportunity seems to have been missed.



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