Study of cosmogenic activation above ground for the DarkSide-20k experiment

The activation of materials due to exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k, currently under construction at the Laboratori Nazionali del Gran Sasso, is a direct detection experiment for galactic dark matter particles, using a two-phase liquid-argon Time Projection Chamber (TPC) filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in 39Ar. Despite the outstanding capability of discriminating γ role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 14.4px; word-spacing: normal; overflow-wrap: normal; text-wrap: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative; \u3e�/β role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 14.4px; word-spacing: normal; overflow-wrap: normal; text-wrap: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative; \u3e� background in argon TPCs, this background must be considered because of induced dead time or accidental coincidences mimicking dark-matter signals and it is relevant for low-threshold electron-counting measurements. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the experiment has been estimated to set requirements and procedures during preparation of the experiment and to check that it is not dominant over primordial radioactivity; particular attention has been paid to the activation of the 120 t of UAr used in DarkSide-20k. Expected exposures above ground and production rates, either measured or calculated, have been considered in detail. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. The activity of 39Ar induced during extraction, purification and transport on surface is evaluated to be 2.8% of the activity measured in UAr by DarkSide-50 experiment, which used the same underground source, and thus considered acceptable. Other isotopes in the UAr such as 37Ar and 3H are shown not to be relevant due to short half-life and assumed purification methods

Report of the Topical Group on Neutrino Properties for Snowmass 2021

Neutrinos are the most elusive among the known elementary particles, because of their feeble interactions with ordinary matter. They are also the most mysterious, because of their tiny masses that suggest a novel mass generating mechanism, their unknown Dirac or Majorana nature, and their big quantum mixing leading to large-amplitude flavor oscillations. This Topical Group focuses on neutrino properties that are not directly investigated in other Topical Groups of the Neutrino Frontier: in particular, the absolute value of the neutrino masses, the Dirac or Majorana nature of neutrinos, their electromagnetic properties, their lifetime, and hypothetical exotic properties.Comment: Topical Group Report for NF05 (Neutrino Frontier Topical Group on Neutrino Properties) for Snowmass 2021. 51 pages excluding reference

1079-102 Correlation between norepinephrine and epinephrine myocardial spillover and tumor necrosis factor-alpha in conventional versus off-pump coronary artery bypass surgery

Background: Complete revascularization obtained by coronary artery bypass surgery does not prevent long term left ventricular remodeling and heart failure development. Periprocedural events linked to different surgical techniques, such as cardiopulmonary bypass with cardioplegic arrest (CABG) versus off-pump procedures may trigger an irreversible microvascular dysfunction or myocytes necrosis and apoptosis. Methods: To test this hypothesis we measured norepinephrine and epinephrine coronary sinus and aortic spillover before and after surgery, simultaneously with Tumor Necrosis Factor-alpha (TNF-alpha) measurements in 30 patients randomized to CABG (n=15), or off-pump (n=15) coronary surgery. Plasma catecholamines were assessed by high performance liquid chromatography and TNF-alpha by ELISA. Results: Norepinephrine and epinephrine spillover was similar in the two groups before surgery, being 1.38\ub10.62 and 1.08\ub10.45, respectively. After surgery norepinephrine spillover was 1.43\ub10.56, 0.72\ub10.49 in CABG and off-pump, respectively (P<0.05 CABG versus off-pump, means \ub1SD ). Epinephrine spillover was 1.27\ub10.16 and 0.65\ub10.15 respectively (P<0.05, CABG versus off-pump). TNF-alpha significantly increased only in CABG patients being 22.17\ub16.79 and 35.4\ub15.98, pg/mL, before and after surgery (P<0.05), respectively. After surgery norepinephrine spillover correlated with TNF-alpha levels (P=0.01, R=0.553). Conclusions: Patients undergoing off-pump interventions showed significantly lower catecholamines spillover as compared to CABG, suggesting that the off-pump technique may result less invasive, not only for a lower local and whole body inflammatory response but also for a lower sympathetic drive. For the first time in humans we have detected an increase in epinephrine-spillover after cardiac surgery. Further studies are necessary to evaluate if the short-term advantages observed after off-pump coronary surgery translate into a long-term attenuation of left ventricular remodeling and in the prevention of heart failure progression

Cosmogenic 11C production and sensitivity of organic scintillator detectors to pep and CNO neutrinos

Several possible background sources determine the detectability of pep and CNO solar neutrinos in organic liquid scintillator detectors. Among such sources, the cosmogenic 11C nuclide plays a central role. 11C is produced underground in reactions induced by the residual cosmic muon flux. Experimental data available for the effective cross section for 11C by muons indicate that 11C will be the dominant source of background for the observation of pep and CNO neutrinos. 11C decays are expected to total a rate 2.5 (20) times higher than the combined rate of pep and CNO neutrinos in Borexino (KamLAND) in the energy window preferred for the pep measurement, between 0.8 and 1.3 MeV. This study examines the production mechanism of 11C by muon-induced showers in organic liquid scintillators with a novel approach: for the first time, we perform a detailed ab initio calculation of the production of a cosmogenic nuclide, 11C, taking into consideration all relevant production channels. Results of the calculation are compared with the effective cross sections measured by target experiments in muon beams. This paper also discusses a technique for reduction of background from 11C in organic liquid scintillator detectors, which allows to identify on a one-by-one basis and remove from the data set a large fraction of 11C decays. The background reduction technique hinges on an idea proposed by Martin Deutsch, who suggested that a neutron must be ejected in every interaction producing a 11C nuclide from 12C. 11C events are tagged by a three-fold coincidence with the parent muon track and the subsequent neutron capture on protons.Comment: 11 pages, 6 figures; added one section detailing comparison with previous estimates; added reference

Measurement of the solar 8B neutrino rate with a liquid scintillator target and 3 MeV energy threshold in the Borexino detector

We report the measurement of electron neutrino elastic scattering from 8B solar neutrinos with 3 MeV energy threshold by the Borexino detector in Gran Sasso (Italy). The rate of solar neutrino-induced electron scattering events above this energy in Borexino is 0.217 +- 0.038 (stat) +- 0.008 (syst) cpd/100 t, which corresponds to the equivalent unoscillated flux of (2.4 +- 0.4 (stat) +- 0.1 (syst))x10^6 cm^-2 s^-1, in good agreement with measurements from SNO and SuperKamiokaNDE. Assuming the 8B neutrino flux predicted by the high metallicity Standard Solar Model, the average 8B neutrino survival probability above 3 MeV is measured to be 0.29+-0.10. The survival probabilities for 7Be and 8B neutrinos as measured by Borexino differ by 1.9 sigma. These results are consistent with the prediction of the MSW-LMA solution of a transition in the solar electron neutrino survival probability between the low energy vacuum-driven and the high-energy matter-enhanced solar neutrino oscillation regimes.Comment: 10 pages, 8 figures, 6 table

Recent Borexino results and prospects for the near future

The Borexino experiment, located in the Gran Sasso National Laboratory, is an organic liquid scintillator detector conceived for the real time spectroscopy of low energy solar neutrinos. The data taking campaign phase I (2007 - 2010) has allowed the first independent measurements of 7Be, 8B and pep fluxes as well as the first measurement of anti-neutrinos from the earth. After a purification of the scintillator, Borexino is now in phase II since 2011. We review here the recent results achieved during 2013, concerning the seasonal modulation in the 7Be signal, the study of cosmogenic backgrounds and the updated measurement of geo-neutrinos. We also review the upcoming measurements from phase II data (pp, pep, CNO) and the project SOX devoted to the study of sterile neutrinos via the use of a 51Cr neutrino source and a 144Ce-144Pr antineutrino source placed in close proximity of the active material.Comment: 8 pages, 11 figures. To be published as proceedings of Rencontres de Moriond EW 201