GERDA and LEGEND: Probing the Neutrino Nature and Mass at 100 meV and beyond

The Gerda (GERmanium Detector Array) project, located at Laboratori Nazionali del Gran Sasso (LNGS), was started in 2005, a few years after the claim of evidence for the neutrinoless double beta decay (0νββ) of 76Ge to the ground state of 76Se: it is an ultra-rare process whose detection would directly establish the Majorana nature of the neutrino and provide a measurement of its mass and mass hierarchy. The aim of Gerda was to confirm or disprove the claim by an increased sensitivity experiment. After establishing the new technology of Ge detectors operated bare in liquid Argon and since 2011, Gerda efficiently collected data searching for 0νββ of 76Ge, first deploying the 76Ge-enriched detectors from two former experiments and later new detectors with enhanced signal-to-background rejection, produced from freshly 76Ge-enriched material. Since then, the Gerda setup has been upgraded twice, first in 2013–2015 and later in 2018. The period before 2013 is Phase I and that after 2015 is Phase II. Both the Gerda setup and the analysis tools evolved along the project lifetime, allowing to achieve the remarkable average energy resolution of ∼3.6 and ∼2.6 keV for Coaxial Germanium (Coax) detectors and for Broad Energy Germanium (BEGe), respectively, and the background index of 5.2−1.3+1.6 · 10−4 cts/(keV·kg·yr) in a 230 keV net range centered at Qββ. No evidence of the 0νββ decay at Qββ = 2039.1 keV has been found, hence the limit of 1.8·1026 yr on the half-life (T1/20ν) at 90% C.L. was set with the exposure of 127.2 kg·yr. The corresponding limit range for the effective Majorana neutrino mass mee has been set to 79–180 meV. The Gerda performances in terms of background index, energy resolution and exposure are the best achieved so far by 76Ge double beta decay experiments. In Phase II, Gerda succeeded in operating in a background free regime and set a world record. In 2017, the Legend Collaboration was born from the merging of the Gerda and Majorana Collaborations and resources with the aim to further improve the Gerda sensitivity. First, the Legend200 project, with a mass of up to 200 kg of 76Ge-enriched detectors, aims to further improve the background index down to <0.6 · 10−3 cts/(keV·kg·yr) to explore the Inverted Hierarchy region of the neutrino mass ordering, then the Legend1000 (1 ton of 76Ge-enriched) will probe the Normal Hierarchy. In this paper, we describe the Gerda experiment, its evolution, the data analysis flow, a selection of its results and technological achievements, and finally the design, features and challenges of Legend, the Gerda prosecutor.

Characterization of inverted coaxial $$^{76}$$Ge detectors in GERDA for future double-$$\beta $$ decay experiments

Neutrinoless double-$$\beta $$ β decay of $$^{76}$$ 76 Ge is searched for with germanium detectors where source and detector of the decay are identical. For the success of future experiments it is important to increase the mass of the detectors. We report here on the characterization and testing of five prototype detectors manufactured in inverted coaxial (IC) geometry from material enriched to 88% in $$^{76}$$ 76 Ge. IC detectors combine the large mass of the traditional semi-coaxial Ge detectors with the superior resolution and pulse shape discrimination power of point contact detectors which exhibited so far much lower mass. Their performance has been found to be satisfactory both when operated in vacuum cryostat and bare in liquid argon within the Gerda setup. The measured resolutions at the Q-value for double-$$\beta $$ β decay of $$^{76}$$ 76 Ge ($$Q_{\beta \beta }$$ Q β β = 2039 keV) are about 2.1 keV full width at half maximum in vacuum cryostat. After 18 months of operation within the ultra-low background environment of the GERmanium Detector Array (Gerda) experiment and an accumulated exposure of 8.5 kg$$\cdot $$ · year, the background index after analysis cuts is measured to be $$4.9^{+7.3}_{-3.4}\times 10^{-4} \ \text {counts}/(\text {keV} \cdot \text {kg} \cdot \text {year})$$ 4 . 9 - 3.4 + 7.3 × 10 - 4 counts / ( keV · kg · year ) around $$Q_{\beta \beta }$$ Q β β . This work confirms the feasibility of IC detectors for the next-generation experiment Legend.

A társadalmi struktúra és az oktatás összefüggései a sportiskolák rendszerében

A társadalmi helyzet jelentős szerepet játszik életünkben, így a sportiskolai rendszerben is, különös tekintettel a vizsgálat fókuszában álló köznevelési típusú sportiskolákra. Ezen intézmények célja a sportkarrier támogatása mellett a tanulmányi eredményesség növelése is. Célunk a hazai köznevelési típusú sportiskolákban tanuló diákok szocio-ökonómiai státuszának felmérése. Ehhez a 2016-os Országos Kompetenciamérés 10. évfolyamos tanuló adatbázisát alkalmazva néztük meg a tanulók családi háttérindexét, majd összevetettük az egyéb típusú, nem sportiskolás diákok helyzetével. Eredményeink alapján a sportiskolákban/sporttagozattal rendelkező iskolákban és egyéb iskolákban tanuló diákok családi háttérindexének tekintetében jelentős különbség mutatható ki (p<0,001), habár hasonlóságok is mutatkoztak. Régiós szinten a sportiskolák tekintetében az észak-alföldi és közép-magyarországi régiókban voltak a legalacsonyabb, míg a közép-dunántúli régióban a legmagasabb a családi háttérindex átlaga. A nem sportiskolák esetében az észak-alföldi régióban voltak tapasztalhatóak a legalacsonyabb, míg Budapesten a legmagasabbak a családi háttérindex értékek.The role of social status is significant in our life, including the sports school system, with particular emphasis on educational sports schools which are in the focus of the study. The aim of these institutions is not only to support sports careers but also to improve academic achievement. Our aim is to investigate the socio-economic status of students learning in educational sports schools. For this reason, the National Competency Assessment of 2016 was applied, including the data of the 10th-grade students to investigate their family background index. Then, we compared these data to the characteristics of students learning in other types of schools. Based on our results, there is a significant difference in the family background index of students studying in sports schools and non-sports schools, although similarities have also been found. At the regional level, the average family background index was the lowest in the North Great Plain and Central Hungary, while it was the highest in Central-Transdanubia. In the case of non-sports schools, the family background index values were the lowest in the North Great Plain, while it was the highest in Budapest.

Read-out Electronics and Signal Processing in GERDA and Future Prospects

The GERDA experiment searches for the neutrinoless double beta decay of 76Ge. The experiment is using 36 kg of high-purity germanium detectors, simultaneously as source and detector, deployed into ultra-pure cryogenic liquid argon. GERDA is one the leading experiment in the field, reporting the highest sensitivity on the half-life of 0νββ decay with 1.1·1026 yr, the lowest background index with 6·10−4 cts/(keV·kg·yr) and an excellent energy resolution of 0.12% (FWHM). The search for the 0νββ decay of the isotope 76Ge will be continued in the next years by the LEGEND-200 experiment, that aims to reach a sensitivity up to 1027 yr using 200 kg of enriched HPGe detectors. The preparation of this experiment already started. The basic concepts of the GERDA read-out electronics, obeying both the severe requirements of ultra high radio-purity and cryogenic operation, are summarized. For LEGEND-200 a new electronics design, including a separation of the preamplifier in two stages, has been already designed and realized: results from tests are presented. Additionally, we will introduce the digital signal processing adopted for the energy reconstruction in GERDA and a new implementation of an optimum digital filter by means of the DPLMS method. This method are discussed and the first application to GERDA data are presented.

Highlights from GERDA: Probing the Majorana Neutrino Mass at 100 meV

Since 2010, the Gerda experiment at Laboratori Nazionali del Gran Sasso (LNGS) operates searching for neutrinoless double beta decay ( 0 ν β β ) of 76 Ge to the ground and excited states of 76 Se. 0 ν β β is an ultra-rare process whose detection would directly establish the Majorana nature of the neutrino and provide a direct measurement of its mass. Since the apparatus upgrade in 2013–2015, the collaboration released the third update of the achieved results at the Neutrino 2018 Conference. The hardware upgrade and the fine tuning of the powerful analysis tools to reconstruct the event energy and to discriminate the background allowed the achievement of the energy resolution of 3 keV and 3.6 keV for Broad Energy Germanium (BEGe) and Coaxial Germanium (Coax) detectors, respectively, and an unprecedented low background index of 0.6

A Simple and Inexpensive Clinical Whole Body Counter

SummaryThe conventional radioisotope scanner has been used as a whole body counter. The background index of the system is 10.9 counts per minute per ml of sodium iodide crystal. The sensitivity and derived sensitivity parameters have been evaluated and found to be suitable for clinical studies. The optimum parameters for a single detector at two positions above the lying subject have been obtained. It has been found that for the case of 131I measurement it is possible to assay a source located at any point in the body with coefficient of variation less than 5%. To add to the versatility, a fixed geometry for in-vitro counting of large samples has been obtained. The retention values obtained by the whole body counter have been found to correlate with those obtained by in-vitro assay of urine and stool after intravenous administration of 51Cr-albumin.