Periodic Reporting for period 1 - GanESS (Gaseous detectors for neutrino physics at the European Spallation Source)
Reporting period: 2022-02-01 to 2024-07-31
Neutrinos are the most elusive known particles in the universe. In order to observe these particles very large detectors with several tons (even thousands of tons) of active material have been built. On the other hand, a neutrino-interaction process with a much larger cross-section, called neutrino-nucleus coherent scattering (CEnNS), was predicted more than 40 years ago. In this process the neutrino interacts with the atomic nuclei as a whole instead than with the individual protons and neutrons (or quarks). In this case, the total cross-section for this process is proportional to the square of the number of neutrons resulting in cross-sections that are ~1e4 times larger for large nuclei such as xenon or cesium.
The counter part of this process is that it can only be observed for relatively low energy neutrinos (<30-40 MeV) and, more important, the energy deposited in the detector is incredibly small, near 1 keV.
For this reason, new detector technologies have to be developed to observe and study this process that could open a new window to understand these elusive particles.
In the GanESS project we are developing the high-pressure gas TPC technology to be applied in the search of CEnNS at the European Spallation Source (ESS) that will produce neutrinos as a residue of the neutron production. The high-pressure gas TPC has the advantage of allowing for amplification of the electrons produced by neutrino interactions which should allow for an important energy threshold reduction with respect to current technologies. In addition, the technology also allows operation in the same detector with different gases enlarging the physics potential of this technology.
The counter part of this process is that it can only be observed for relatively low energy neutrinos (<30-40 MeV) and, more important, the energy deposited in the detector is incredibly small, near 1 keV.
For this reason, new detector technologies have to be developed to observe and study this process that could open a new window to understand these elusive particles.
In the GanESS project we are developing the high-pressure gas TPC technology to be applied in the search of CEnNS at the European Spallation Source (ESS) that will produce neutrinos as a residue of the neutron production. The high-pressure gas TPC has the advantage of allowing for amplification of the electrons produced by neutrino interactions which should allow for an important energy threshold reduction with respect to current technologies. In addition, the technology also allows operation in the same detector with different gases enlarging the physics potential of this technology.
We have installed and started the operation of the Gaseous Prototype (Gap) detector at the DIPC. This detector, allows operation at very high pressures (50 bar) and in a first stage will allow for testing and understanding the best solution for the implementation of the amplification region in the final GanESS detector, as well as the different read-out possibilities.The initial operation of the GaP detector with pure argon and low energy gamma-ray radioactive sources has allowed to prove the capabilities of this technology to reach energy thresholds of 1 keV or less. Currently we are operating the detector with a mixture of argon and xenon at 0.1% which allows shifting the argon light to the xenon emission spectra. Initial results with this mixture show a large increase in the number of photons detected when compared to pure argon and also larger stability to high voltages.
In parallel to the progress with the GaP detector, we have been working on the neutron background characterisation at the ESS. We are working on the comparison of total neutron flux in different possible operation areas at the ESS using Geant4 and MCNP Monte-Carlo libraries. In order to characterise this flux we have developed together with other colleagues at DIPC and University of Chicago, a neutron camera that will allow not only for a total measurement of the neutron flux, but also for a spectrum measurement and directionality. This camera will be deployed at the ESS once it starts operations and will allow for validation of the simulations.
In parallel to the progress with the GaP detector, we have been working on the neutron background characterisation at the ESS. We are working on the comparison of total neutron flux in different possible operation areas at the ESS using Geant4 and MCNP Monte-Carlo libraries. In order to characterise this flux we have developed together with other colleagues at DIPC and University of Chicago, a neutron camera that will allow not only for a total measurement of the neutron flux, but also for a spectrum measurement and directionality. This camera will be deployed at the ESS once it starts operations and will allow for validation of the simulations.
The development of the GaP prototype has been a fundamental step forward for the success of of the project, as it will be used as a test bench for the technology that will finally be implemented in the GanESS detector. In that direction, we have started collaborating with other international groups towards the possibility of implanting SiPMs read-out in our system. In particular, we want to adapt the electronics developed for the DarkSide dark matter experiment. Simulation of this solutions have been performed and we are already producing an adaptation of such electronics for our project.
During the next months, we expect to finish the data taking with these different configurations of the detector and plan to move forward on the final detector design.
Another fundamental step for the project is the formalisation of the experimental site at the ESS. We are working towards a collaboration with the ESS to find the best possible place and help on the neutron characterisation.
During the next months, we expect to finish the data taking with these different configurations of the detector and plan to move forward on the final detector design.
Another fundamental step for the project is the formalisation of the experimental site at the ESS. We are working towards a collaboration with the ESS to find the best possible place and help on the neutron characterisation.