Kara Marie Lynch has received the 2013 Institute of Physics-Nuclear Physics Group’s Early Career Prize, which is awarded to young scientists with less than five years of research. Candidates are nominated by their supervisor or another academic with whom they have closely worked during their research.

Kara worked at CERN under CERN’s Doctoral Student scheme, while she was affiliated with the University of Manchester, the academic institution that awarded her PhD degree. Kara says: “Having studied nuclear physics during my undergraduate degree at the University of York, I was looking to continue my studies in the field. Through contacting the University of Manchester, I heard about CERN’s Doctoral Student programme and the possibility of a PhD working on the new CRIS experiment at ISOLDE”.

In September 2010 Kara arrived at CERN to work on the CRIS beamline in the ISOLDE nuclear physics facility. At that time, the CRIS (Collinear Resonance Ionization Spectroscopy) experiment was a new laser spectroscopy experiment at ISOLDE, having only been commissioned 2 years previously. The next three years were spent working with the rest of the CRIS collaboration to test the technique and optimise the experimental setup.

She submitted her thesis in the beginning of August and passed her viva on 19^th September 2013. Her thesis focused on using the selectivity of the CRIS technique to perform Laser Assisted Nuclear Decay Spectroscopy. This combines the high sensitivity of laser spectroscopy with decay spectroscopy, allowing the nuclear structure of the very rare and neutron-deficient francium isotopes to be studied.

Kara and colleagues working through the night in summer 2012 to collect measurements of francium @ Kieran Flanagan.

Maria J. G. Borge, ISOLDE’s spokesperson, explains: “it is very hard to separate well heavy nuclei due to the presence of isobaric contaminants very close in mass. The innovative  collinear resonant ionization technique (CRIS) combined with decay spectroscopy is helpful when the beam is not pure. This new technique has allowed for the measurement of the hyperfine structure and the determination of the fundamental properties of nuclei, such as the radius, and shape in a region of interesting shape coexistence. Maria Borge adds: “It is important to understand the nuclear structure for these heavy nuclei and explore the shape evolution. The modification of the shell structure, as well as the study of new collective modes. of exotic nuclei are important sources of information.  Clearly, CERN is the only place where you can address this type of studies in the actinide region.”

Kara explains: “With the CRIS technique, we are using lasers to probe the hyperfine structure of nuclear isotopes. By overlapping pulses of laser light with an atomic bunch, we are able to resonantly excite and ionize the isotope of interest. From the hyperfine structure of the isotope, we can deduce properties of the nucleus such as the nuclear spin, magnetic moment, quadrupole moment, change in mean-square charge radius and the isotope shift. In addition, we can select the different nuclear states present in the atomic beam (either ground state or isomeric) from a characteristic hyperfine resonance. This allows us to perform laser assisted nuclear decay spectroscopy on a pure ground state or isomeric beams. “

ISOLDE wants to go as far from stability as possible and this technique is more sensitive than some of the other techniques that have been used in the past. With a yield of only a few 100 atoms per second, the rare heavy nuclei (such as francium) have been studied.

The ISOLDE collaboration rightly feels proud, as it is the first time that a student working under CERN’s Doctoral programme is awarded this prestigious prize, which also recognizes the students' hard work during their stay at CERN and reflects the potentiality of the programme. Maria Borge says: “We hope to enlarge the number of doctoral students working at ISOLDE through this programme.”

Kara has recently started her postdoc at KU Leuven in Belgium, and she will continue to work at the CRIS facility. The University of Manchester and KU Leuven are the two main collaborators on the CRIS experiment. “The postdoc at KU Leuven will give me the chance to perform more experiments on the francium isotopes, in order to measure isotopes further from stability and to tackle some of the questions that arose during my PhD” adds Kara.

Kara will be mostly based at CERN for the next year and she will soon add an addendum to the CRIS experimental proposal for francium. She adds that “There are other experimental proposals accepted at CRIS, so in the meantime I will help prepare for these experiments for when ISOLDE starts up again in the middle of next year”.