The Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND)

The observation of neutrinoless double-beta decay (0${\nu}{\beta}{\beta}$) would show that lepton number is violated, reveal that neutrinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of $\sim$0.1 count /(FWHM$\cdot$t$\cdot$yr) in the region of the signal. The current generation $^{76}$Ge experiments GERDA and the MAJORANA DEMONSTRATOR utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0${\nu}{\beta}{\beta}$ signal region of all 0${\nu}{\beta}{\beta}$ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale $^{76}$Ge experiment. The collaboration aims to develop a phased 0${\nu}{\beta}{\beta}$ experimental program with discovery potential at a half-life approaching or at $10^{28}$ years, using existing resources as appropriate to expedite physics results.Comment: Proceedings of the MEDEX'17 meeting (Prague, May 29 - June 2, 2017

Development of methods for the preparation of radiopure ⁸²Se sources for the SuperNEMO neutrinoless double-beta decay experiment

A radiochemical method for producing 82Se sources with an ultra-low level of contamination of natural radionuclides (40K, decay products of 232Th and 238U) has been developed based on cation-exchange chromatographic purification with reverse removal of impurities. It includes chromatographic separation (purification), reduction, conditioning (which includes decantation, centrifugation, washing, grinding, and drying), and 82Se foil production. The conditioning stage, during which highly dispersed elemental selenium is obtained by the reduction of purified selenious acid (H2SeO3) with sulfur dioxide (SO2) represents the crucial step in the preparation of radiopure 82Se samples. The natural selenium (600 g) was first produced in this procedure in order to refine the method. The technique developed was then used to produce 2.5 kg of radiopure enriched selenium (82Se). The produced 82Se samples were wrapped in polyethylene (12 μm thick) and radionuclides present in the sample were analyzed with the BiPo-3 detector. The radiopurity of the plastic materials (chromatographic column material and polypropylene chemical vessels), which were used at all stages, was determined by instrumental neutron activation analysis. The radiopurity of the 82Se foils was checked by measurements with the BiPo-3 spectrometer, which confirmed the high purity of the final product. The measured contamination level for 208Tl was 8-54 μBq/kg, and for 214Bi the detection limit of 600 μBq/kg has been reached.</p

Measurement of the 2νββ decay half-life of 150Nd and a search for 0νββ decay processes with the full exposure from the NEMO-3 detector

We present results from a search for neutrinoless double-β (0νββ) decay using 36.6 g of the isotope 150Nd with data corresponding to a live time of 5.25 y recorded with the NEMO-3 detector. We construct a complete background model for this isotope, including a measurement of the two-neutrino double-β decay half-life of T2ν 1=2 ¼ ½9.34 0.22ðstatÞ þ0.62 −0.60 ðsystÞ × 1018 y for the ground state transition, which represents the most precise result to date for this isotope. We perform a multivariate analysis to search for 0νββ decays in order to improve the sensitivity and, in the case of observation, disentangle the possible underlying decay mechanisms. As no evidence for 0νββ decay is observed, we derive lower limits on half-lives for several mechanisms involving physics beyond the standard model. The observed lower limit, assuming light Majorana neutrino exchange mediates the decay, is T0ν 1=2 > 2.0 × 1022 y at the 90% C.L., corresponding to an upper limit on the effective neutrino mass of hmνi < 1.6–5.3 eV

ПЛАНИРУЕМОЕ МНОГОЦЕНТРОВОЕ РАНДОМИЗИРОВАННОЕ КЛИНИЧЕСКОЕ ИССЛЕДОВАНИЕ II ФАЗЫ: НЕОАДЪЮВАНТНАЯ ХИМИОЛУЧЕВАЯ ТЕРАПИЯ С ПОСЛЕДУЮЩЕЙ ГАСТРЭКТОМИЕЙ D2 И АДЪЮВАНТНОЙ ХИМИОТЕРАПИЕЙ У БОЛЬНЫХ МЕСТНОРАСПРОСТРАНЕННЫМ РАКОМ ЖЕЛУДКА

Introduction. The prognosis for surgical treatment of locally advanced gastric cancer remains disappointing. Neoadjuvant chemo-radiation therapy is relatively new and the least researched method of treatment, it is attracting more and more attention, mainly abroad in recent years. The aims of neoadjuvant therapy is the earliest start of systemic therapy, damage of the primary tumor and regional metastases, an increase in the percentage of radical operations, improving treatment outcome. Material and methods. The planning study is a multicenter, randomized clinical phase II trial. Patients of the first (experimental) group will be treated as the followes: neoadjuvant chemo-radiotherapy (total tumor dose of 46 Gy in 23 fractions with the concurrent modified CapOX scheme) followed by D2 gastrectomy and adjuvant chemotherapy. Patients of the second (control) group will be treated with D2 gastrectomy and adjuvant chemotherapy. Adjuvant chemotherapy will be carried out under the following schemes (optional for the researchers): CapOX or FOLFOX. Toxicity evaluation of neoadjuvant chemo-radiotherapy and adjuvant chemotherapy will be conducted with NCI CTC Toxicity Scale Version 3.0. The main objectives of the trial are to assess the safety and immediate effectiveness of neoadjuvant chemo-radiotherapy according to the criteria of the frequency and severity of postoperative complications and mortality, and tumor response. We are planning to include 80 patients with morphologically confirmed gastric cancer сT2–4N1–3, сT3–4N0–3; М0. The proposed trial will be carried out in accordance with the principles of the Helsinki Declaration, it has been approved by local ethic committees of the participated institutions. Results. As a result of this multicenter randomized trial it is planned to show the reproducibility of obtained in MRRC and a number of foreign centers results – that is, the safety and high immediate effectiveness of neoadjuvant chemo-radiotherapy in patients with locally advanced gastric cancer. Conclusion. If we reach the goals of the planning trial, the results would allow to reasonably recommend the start of large international phase III trials for the final evaluation of the proposed neoadjuvant treatment as a standard one in patients with locally advanced gastric cancer.Введение. Прогноз при хирургическом лечении местнораспространенного рака желудка остается неутешительным. Неоадъювантная химиолучевая терапия является относительно новым и наименее исследованным методом лечения, привлекающим к себе в последние годы все большее внимание, преимущественно за рубежом. Цели неоадъювантной терапии состоят в максимально раннем начале системной терапии, повреждении первичной опухоли и регионарных метастазов, увеличении процента выполнения радикальных операций, улучшении результатов лечения. Материал и методы. Исследование является многоцентровым рандомизированным клиническим исследованием II фазы. Больным первой (исследуемой) группы будет проведено лечение в составе: неоадъювантная химиолучевая терапия (СОД 46 Гр за 23 фракции на фоне модифицированного режима CapOX) с последующей гастрэктомией D2 и адъювантной химиотерапией. Больным второй (контрольной) группы будет выполнена гастрэктомия D2 и адъювантная химиотерапия. Адъювантная химиотерапия будет проводиться по следующим схемам (на выбор исследователя): САРОX или FOLFOX. Оценка токсичности неоадъювантной химиолучевой терапии и адъювантной химиотерапии будет проводиться с помощью шкалы токсичности NCI CTC, версия 3.0. Основные цели состоят в оценке безопасности и непосредственной эффективности неоадъювантной химиолучевой терапии по критерию частоты и степени выраженности послеоперационных осложнений и летальности, и терапевтического патоморфоза. Планируется включение 80 больных морфологически верифицированным раком желудка сT2–4N1–3, сT3–4N0–3; М0. Исследование выполняется в соответствии с принципами Хельсинкской декларации, оно одобрено локальными этическими комитетами учреждений-соисполнителей. Результаты. В результате проведения данного многоцентрового рандомизированного исследования планируется показать воспроизводимость полученных в МРНЦ и ряде зарубежных Центров результатов – то есть безопасность и высокую непосредственную эффективность неоадъювантной химиолучевой терапии у больных местнораспространенным раком желудка. Заключение. В случае достижения поставленных целей полученные результаты позволят обоснованно рекомендовать проведение крупных международных исследований III фазы для окончательного изучения предложенного метода в качестве стандартного у больных местнораспространенным раком желудка

Final results on ⁸²Se double beta decay to the ground state of ⁸²Kr from the NEMO-3 experiment

Using data from the NEMO-3 experiment, we have measured the two-neutrino double beta decay ( 2\nu \beta \beta) half-life of ^{82}Se as T_{\smash {1/2}}^{2\nu } \!=\! \left[ 9.39 \pm 0.17\left( \text{ stat }\right) \pm 0.58\left( \text{ syst }\right) \right] \times 10^{19} y under the single-state dominance hypothesis for this nuclear transition. The corresponding nuclear matrix element is \left| M^{2\nu }\right| = 0.0498 \pm 0.0016. In addition, a search for neutrinoless double beta decay ( 0\nu \beta \beta) using 0.93 kg of ^{82}Se observed for a total of 5.25 y has been conducted and no evidence for a signal has been found. The resulting half-life limit of T_{1/2}^{0\nu } > 2.5 \times 10^{23} \,\text{ y } \,(90\%\,\text{ C.L. }) for the light neutrino exchange mechanism leads to a constraint on the effective Majorana neutrino mass of \langle m_{\nu } \rangle < \left( 1.2{-}3.0\right) \,\text{ eV }, where the range reflects 0\nu \beta \beta nuclear matrix element values from different calculations. Furthermore, constraints on lepton number violating parameters for other 0\nu \beta \beta mechanisms, such as right-handed currents, majoron emission and R-parity violating supersymmetry modes have been set

Calorimeter development for the SuperNEMO double beta decay experiment

SuperNEMO is a double-β decay experiment, which will employ the successful tracker–calorimeter technique used in the recently completed NEMO-3 experiment. SuperNEMO will implement 100 kg of double-β decay isotope, reaching a sensitivity to the neutrinoless double-β decay (0νββ) half-life of the order of 1026 yr, corresponding to a Majorana neutrino mass of 50–100 meV. One of the main goals and challenges of the SuperNEMO detector development programme has been to reach a calorimeter energy resolution, ΔE∕E, around 3%∕E(MeV) σ, or 7%∕E(MeV) FWHM (full width at half maximum), using a calorimeter composed of large volume plastic scintillator blocks coupled to photomultiplier tubes. We describe the R&D programme and the final design of the SuperNEMO calorimeter that has met this challenging goal

Measurement of the 2 nu beta beta decay half-life and search for the 0 nu beta beta decay of Cd-116 with the NEMO-3 detector

The NEMO-3 experiment measured the half-life of the 2 ν β β decay and searched for the 0 ν β β decay of 116 Cd . Using 410 g of 116 Cd installed in the detector with an exposure of 5.26 y, ( 4968 ± 74 ) events corresponding to the 2 ν β β decay of 116 Cd to the ground state of 116 Sn have been observed with a signal to background ratio of about 12. The half-life of the 2 ν β β decay has been measured to be T 2 ν 1 / 2 = [ 2.74 ± 0.04 ( stat ) ± 0.18 ( syst ) ] × 1 0 19     y . No events have been observed above the expected background while searching for 0 ν β β decay. The corresponding limit on the half-life is determined to be T 0 ν 1 / 2 ≥ 1.0 × 1 0 23     y at the 90% C.L. which corresponds to an upper limit on the effective Majorana neutrino mass of ⟨ m ν ⟩ ≤ 1.4 – 2.5     eV depending on the nuclear matrix elements considered. Limits on other mechanisms generating 0 ν β β decay such as the exchange of R-parity violating supersymmetric particles, right-handed currents and majoron emission are also obtained