An interdisciplinary group of researchers led by scientists from DIPC, Ikerbasque and UPV/EHU, has actually shown that it is possible to construct an ultra-sensitive sensing unit based upon a brand-new fluorescent particle able to identify the nuclear decay secret to understanding whether a neutrino is its own antiparticle.
The outcomes of this research study, released in the prominent journal Nature, have fantastic possible to figure out the nature of the neutrino and therefore address essential concerns about the origin of the Universe.
Why is our Universe made from matter? Why does whatever exist as we understand it? These concerns are connected to among the most essential unsolved issues in particle physics. This issue is that of the nature of the neutrino, which might be its own antiparticle, as argued by the regrettable Italian genius Ettore Majorana practically a century back. If this were so, it might describe the strange cosmic asymmetry in between matter and antimatter.
Indeed, we understand that the Universe is made practically solely of matter. However, the Big Bang theory anticipates that the early Universe included the very same quantity of matter and antimatter particles. This forecast follows the “small Big Bangs” that form in proton crashes at CERN’s huge LHC accelerator, where an in proportion production of particles and antiparticles is constantly observed. So, where did the antimatter of the early Universe go? A possible system indicate the presence of heavy neutrinos that were its own antiparticle, and for that reason, might decay into both matter and antimatter. If a 2nd phenomenon happens, called infraction of charge and parity (that is, if the neutrino somewhat prefers in its decay the production of matter over that of antimatter), then it might have injected an excess of the very first over the 2nd. After all the matter and antimatter in the Universe were wiped out (with the exception of this little excess), the outcome would be an universes made just of matter, of the leftovers from the Big Bang. We might state that our Universe is the residue of a shipwreck.
It is possible to show that the neutrino is its own antiparticle by observing an unusual kind of nuclear procedure called neutrinoless double beta decay (bb0nu), in which simultaneously 2 neutrons (n) of the nucleus are changed into protons (p) while 2 electrons (e) are released out of the atom. This procedure can take place in some unusual isotopes, such as Xenon-136, which has in its nucleus 54 p and 82 n, in addition to 54 e when is neutral. The NEXT experiment (directed by J.J. Gómez-Cadenas, DIPC and D. Nygren, UTA), situated in the underground lab of Canfranc (LSC), tries to find these decays utilizing high pressure gas chambers.
When a Xe-136 atom goes through spontaneous bb0nu decay, the outcome of the procedure is the production of a two times as charged ion of Barium-136 (Ba2+); with 54 e and a nucleus made from 56 p and 80 n; and 2 electrons (Xe à Ba2+ + 2e).
So far, the NEXT experiment has actually concentrated on observing these 2 electrons, whose signal is really particular of the procedure. However, the bb0nu procedure that is indicated to be observed is exceptionally unusual and the signal that is anticipated is of the order of one bb0nu decay per lots of gas and year of direct exposure. This really weak signal can be entirely masked by background sound due to the common natural radioactivity. However, if in addition to observing the 2 electrons, the barium ionized atom is likewise spotted, the background sound can be minimized to no, given that natural radioactivity does not produce this ion. The issue is that observing a single ion of Ba2+ in the middle of a big bb0nu detector is technically so difficult that up until just recently it was thought about basically impractical. However, a variety of current works, the current of which has actually simply been released in the journal Nature, recommend that the task might be practical after all.
The work, developed and led by the scientists F.P. Cossío, Professor at the University of the Basque Country (UPV/EHU) and Scientific Director of Ikerbasque, and J.J. Gómez-Cadenas, Professor Ikerbasque at the Donostia International Physics Center (DIPC), consists of an interdisciplinary group with researchers from DIPC, the UPV/EHU, Ikerbasque, the Optics Laboratory of the University of Murcia (LOUM), the Materials Physics Center (CFM, a joint center CSIC-UPV/EHU), POLYMAT, and the University of Texas at Arlington (UTA). Gómez-Cadenas has actually mentioned that “the result of this interdisciplinary collaboration that combines, among other disciplines, particle physics, organic chemistry, surface physics and optics, is a clear example of the commitment that DIPC has recently shown to developing new research lines. The purpose is not only to generate knowledge in other fields, different from the centre’s usual ones, but also to look for hybrid grounds and create interdisciplinary projects that, in many cases, like this one, can be the most genuine”.
The research study is based upon the concept, proposed by among the authors of the short article, the prominent researcher D. Nygren (developer, to name a few gadgets of the Time Projection Chamber innovation used by lots of particle physics experiment, consisting of NEXT). In 2016, Nygren proposed the expediency to record Ba2+ with a particle efficient in forming a supramolecular complex with it and to offer a clear signal when this happens, therefore yielding an ideal molecular indication. Nygren and his group at UTA then entered into creating “on-off” signs, in which the signal of the particle is extremely improved when a supra-molecular complex is formed. The group led by Cossío and Gómez-Cadenas has actually followed a various course, creating a fluorescent bicolor indication (FBI) which integrates a big strength improvement and a remarkable color shift when the particle records Ba2+. The synthesis of FBI was done under the instructions of DIPC scientist I. Rivilla. If an FBI particle without any barium is brightened with ultraviolet light, it produces fluorescence in the series of thumbs-up, with a narrow emission spectrum of about 550 nm. However, when this particle records Ba2+, its emission spectrum shifts towards blue (420 nm). The mix of both functions leads to an amazing improvement of the signal, therefore making it really appropriate for a future Ba2+ detector.
It is intriguing to keep in mind that the speculative multiphoton microscopy systems utilized in the LOUM by P. Artal’s group for the green/blue spectral detection are based upon those established formerly for imaging the cornea of the human eye in vivo. This is an example of interlacing making use of a unique innovation on the planet for biomedical applications on an essential issue of particle physics. “The effort to combine basic science and new instrumental implementations is essential to open new research avenues to answer the many questions that we scientists ask ourselves every day,” states J.M. Bueno, Professor of Optics at LOUM.
As Cossío has actually described, “the most difficult task in the chemical part of the work was to design a new molecule that would meet the strict (almost impossible) requirements imposed by the NEXT experiment. This molecule had to be very bright, capture barium with extreme efficiency (bb0nu is a very rare event and no cation could be wasted) and emit a specific signal that would allow the capture to be detected without background noise. In addition, the chemical synthesis of the new FBI sensor had to be efficient in order to have enough ultra-pure samples for installation within the detector. The most rewarding part was to check that, after many efforts by this multidisciplinary team, actually our specific and ultra-sensitive FBI sensor worked as planned”.
Besides the style and characterization of FBI, the paper uses the very first presentation of the development of a supramolecular complex in dry medium. This landmark outcome has actually been attained preparing a layer of FBI signs compressed over a silica pellet and vaporizing over such a layer a salt of barium perchlorate. Z. Freixa, Ikerbasque Professor at the UPV/EHU states, with a smile: “the preparation of FBI on silica has been a quick-but-not-so-dirty solution for this proof of concept. A bit of home alchemy”. The vacuum sublimation experiment was done by the CSIC researcher at CFM C. Rogero and her trainee P. Herrero-Gómez. Rogero, a professional in physics of surface areas states: “it was one of those Eureka moment, when we realized that we had in my lab just the tools to carry on the experiment. We evaporated the perchlorate and got FBI shinning in blue almost at the first attempt”
The next action of this research study job is the building and construction of an FBI based sensing unit for the detection of the neutrinoless double beta decay or bb0nu, for which Gomez-Cadenas, F. Monrabal from DIPC and D. Nygren and partners at UTA are establishing a conceptual proposition.
This work is a considerable advance towards constructing a future “barium-tagging” NEXT experiment to search for noise-free bb0nu occasions through the recognition of the 2 electrons and the barium atom produced in the response. This experiment would have a fantastic possible to discover if the neutrino is its own antiparticle, which might result in address essential concerns about the origin of the Universe.
Reference: “Fluorescent bicolour sensor for low-background neutrinoless double β decay experiments” by Iván Rivilla, Borja Aparicio, Juan M. Bueno, David Casanova, Claire Tonnelé, Zoraida Freixa, Pablo Herrero, Celia Rogero, José I. Miranda, Rosa M. Martínez-Ojeda, Francesc Monrabal, Beñat Olave, Thomas Schäfer, Pablo Artal, David Nygren, Fernando P. Cossío and Juan J. Gómez-Cadenas, 22 June 2020, Nature.