The first search for bosonic super-WIMPs with masses up to 1 MeV/c2^2 with GERDA

We present the first search for bosonic super-WIMPs as keV-scale dark matter candidates performed with the GERDA experiment. GERDA is a neutrinoless double-beta decay experiment which operates high-purity germanium detectors enriched in $^{76}$Ge in an ultra-low background environment at the Laboratori Nazionali del Gran Sasso (LNGS) of INFN in Italy. Searches were performed for pseudoscalar and vector particles in the mass region from 60 keV/c$^2$ to 1 MeV/c$^2$. No evidence for a dark matter signal was observed, and the most stringent constraints on the couplings of super-WIMPs with masses above 120 keV/c$^2$ have been set. As an example, at a mass of 150 keV/c$^2$ the most stringent direct limits on the dimensionless couplings of axion-like particles and dark photons to electrons of $g_{ae} < 3 \cdot 10^{-12}$ and ${\alpha'}/{\alpha} < 6.5 \cdot 10^{-24}$ at 90% credible interval, respectively, were obtained.Comment: 6 pages, 3 figures, submitted to Physical Review Letters, added list of authors, updated ref. [21

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

ИНТРАПЕРИТОНЕАЛЬНОЕ ХИМИОПЕРФУЗИОННОЕ ЛЕЧЕНИЕ ДИССЕМИНИРОВАННОГО РАКА ЯИЧНИКА ДИОКСАДЭТОМ В СРАВНЕНИИ С ЦИСПЛАТИНОМ В ЭКСПЕРИМЕНТЕ

Comparative study of antitumor activity of cisplatin and dioxadet in chemoperfusion treatment was carried out on ascitic ovarian cancer model in 172 Vistar female rats. Ovarian cancer was inoculated intraperitoneally at a volume of 0.5 ml per rat with concentration of tumor cells 2×107 / ml. The drugs were administered once in 48 hours after inoculation of ovarian cancer in maximum tolerated doses (MTD). Normothermic intraperitoneal chemoperfusion (IPEC) and hyperthermic intraperitoneal chemoperfusion (HIPEC) were performed with cisplatin or dioxadet at doses that were 5−20 times higher than those for their standard intraperitoneal administration. Antitumor effects of the drugs were estimated in increase of median survival time (MST). In case of IPEC and HIPEC cisplatin increased the MST by 317  % and 183  % (р&lt;0.05) respectively, when dioxadet increased the MST by 244  % and 444  % (р&lt;0.05) respectively compared to the control group of animals that didn’t receive any treatment. HIPEC with dioxadet is the most effective regimen in experimental treatment of advanced ovarian cancer

Оценка противоопухолевой активности 2-[3-(2-хлорэтил)- 3-нитрозоуреидо]-1,3-пропандиола (хлонизола) у мышей C57BL/6 с трансплантированной интракраниально меланомой B16

Background. The arsenal of antitumor drug therapy for melanoma brain metastases is limited. The search and study of new agents capable to penetrate the blood-brain barrier and provide a therapeutic effect against intracranial tumors remains an unmet clinical need. The aim is to evaluate the antitumor activity of the domestic derivative of nitrosoalkylureas, chlonisol, in mice with intracranially transplanted syngeneic B16 melanoma. Methods. The experiment was carried out in 18 female inbred C57BL/6 mice. After intracranial tumor transplantation, performed according to modified technique, the animals were randomized into two groups: I. Control (n = 10) – the animals were injected with normal saline 10 ml/kg intraperitoneally; II. Chlonisol (n = 8) – the animals were treated with the test compound at a dose of 15 mg/kg in normal saline intraperitoneally. The single administration of normal saline and chlonisol was performed 24 hours after tumor transplantation. The end point of the study was overall survival (OS) of the animals. Results. Compared with the control group, administration of chlonisol significantly increased the median OS of mice from 13 to 18 days (log rank test, p = 0.0005). Chlonisol significantly decreased the risk of death by 71 % compared with the control group (HR = 0.29; 95 %CI 0.10–0.82). By the 15th day after intracranial transplantation of B16 melanoma, all 10 mice in the control group died from intracerebral tumors (100 %), whereas in the chlonisol group only 2 out of 8 (25 %) mice died (Fisher's exact test, p = 0.0015). Conclusion. Despite the exploratory nature of the present study, it provides a good starting point for further research of chlonisol in brain tumors.Актуальность. Арсенал средств противоопухолевой терапии метастазов меланомы в головной мозг ограничен. Актуальным остаётся поиск и изучение новых средств, способных проникать через гематоэнцефалический барьер и оказывать терапевтический эффект в отношении интракраниальных опухолевых очагов. Цель. Оценить противоопухолевую активность отечественного производного нитрозоалкилмочевин хлонизола у мышей с трансплантированной интракраниально сингенной меланомой B16. Методы. Эксперимент был проведён на 18 инбредных мышах самках линии C57BL/6. После интракраниальной трансплантации опухоли, выполненной по модифицированной методике, животные были рандомизированы в две группы: I. Контроль (n = 10) – животным однократно внутрибрюшинно вводили 0,9 % раствор натрия хлорида в объёме 10 мл/кг; II. Хлонизол (n = 8) – животным однократно внутрибрюшинно вводили тестируемое соединение в дозе 15 мг/кг в 0,9 % раствора натрия хлорида. Введение 0,9 % раствора натрия хлорида и хлонизола выполняли через 24 часа после трансплантации опухоли. Конечной точкой исследования была оценка общей выживаемости (ОВ) животных. Результаты. По сравнению с контрольной группой введение хлонизола значимо увеличило медиану ОВ мышей с 13 до 18 дней (логранговый тест, p = 0,0005). В группе хлонизола установлено достоверное снижение риска смерти животных на 71 % по сравнению с контрольной группой (HR = 0,29; 95% CI 0,10–0,82). К 15-му дню после интракраниальной трансплантации меланомы В16 все 10 мышей контрольной группы погибли от внутримозговой опухоли (100 %), а в группе хлонизола погибли 2 из 8 (25 %) мышей (точный критерий Фишера, p = 0,0015). Заключение. Несмотря на разведочный характер представленного исследования, его результаты могут служить обоснованием для дальнейшего изучения хлонизола при опухолевых поражениях головного мозга

Calibration of the Gerda experiment

The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double-β decay in 76Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The experimental signature of the decay is a monoenergetic signal at Qββ= 2039.061 (7) keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double-β decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular 228Th calibrations. In this work, we describe the calibration process and associated data analysis of the full Gerda dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years

Final Results of GERDA on the Search for Neutrinoless Double-β\beta Decay

The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay of $^{76}$Ge, whose discovery would have far-reaching implications in cosmology and particle physics. By operating bare germanium diodes, enriched in $^{76}$Ge, in an active liquid argon shield, GERDA achieved an unprecedently low background index of $5.2\times10^{-4}$ counts/(keV$\cdot$kg$\cdot$yr) in the signal region and met the design goal to collect an exposure of 100 kg$\cdot$yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg$\cdot$yr of total exposure. A limit on the half-life of $0\nu\beta\beta$ decay in $^{76}$Ge is set at $T_{1/2}>1.8\times10^{26}$ yr at 90% C.L., which coincides with the sensitivity assuming no signal.Comment: 7 pages, 3 figures, submitted to Physical Review Letter

Pulse shape analysis in Gerda Phase II

The GERmanium Detector Array (Gerda) collaboration searched for neutrinoless double-β decay in 76Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del Gran Sasso of INFN. After Phase I (2011–2013), the experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase of mass by point-contact germanium detectors that improved the half-life sensitivity of Phase II (2015–2019) by an order of magnitude. At the core of the background mitigation strategy, the analysis of the time profile of individual pulses provides a powerful topological discrimination of signal-like and background-like events. Data from regular 228Th calibrations and physics data were both considered in the evaluation of the pulse shape discrimination performance. In this work, we describe the various methods applied to the data collected in Gerda Phase II corresponding to an exposure of 103.7 kg year. These methods suppress the background by a factor of about 5 in the region of interest around Qββ=2039 keV, while preserving (81±3)% of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis