Search for two-photon emission in 98Mo

Lead Research Organisation: University of York
Department Name: Physics


Electromagnetic transitions between atomic or nuclear energy levels generally proceed by emission or absorption of a single photon, but the next order process is two-photon emission which is about 10000 times weaker. Such a process is very familiar in atomic systems but barely studied in the nuclear case because Compton-scattered gamma rays may be mistaken for two-photon emission. The best cases to study this phenomenon are therefore those where emission of a single photon is forbidden and this is the case where initial and final states have spin zero. In this case, the first order process is emission of a conversion electron which has a very different character to two-photon emission. A handful of cases of two-photon emission in nuclei were studied 20 years ago and earlier. These showed that there was an unexpected intereference between electric and magnetic dipole transitions in the two-photon decay. Unfortunately, this process was never fully understood. We hope to shine new light on this with a very sensitive measurement using the state-of-the-art gamma-ray detector array, Gammasphere situated at Argonne National Laboratory. This grant is to carry out an approved experimental study of two-photon emission in 98-Mo using Gammasphere.


10 25 50
Description An experiment was carried out to measure two-photon emission in 98Mo. An upper limit was set on this value and a paper with this result has been published.
Exploitation Route It might encourage further pure research on this topic.
Sectors Education

Description The impact is in the field of nuclear physics. No societal impact is envisaged.
Description Nuclear physics outreach work 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact For the last ten years, I have been involved in a whole range of outreach activities related to nuclear physics, from lectures to local groups e.g. astronomical societies to lectures at major science festivals. A major focus has been on providing continuous professional development courses for teachers. These have taken place at several science learning centres including National Science Learning Centre in York. In addition, they have been given at Rutherford Lab and elsewhere. Around 500 teachers have been reached over the years.
Year(s) Of Engagement Activity 2006,2007,2008,2009,2010