The Scintillator Upgrade of IceTop: Performance of the prototype array

The IceCube Collaboration foresees to upgrade IceTop, the present surface array, with scintillator detectors augmented by radio antennas. As one of several goals the scintillator detectors will be used to measure and mitigate the effects of snow accumulation on the IceTop tanks: the increasing energy threshold and efficiency loss are nowadays the sources of the largest systematic uncertainties in shower reconstruction and mass composition analysis. In addition, the upgrade will provide useful experience for the development of next generation neutrino detectors proposed for the South Pole. In the Austral summer season, 2017-2018 two full "stations" were installed near the center of the IceTop array. Each station features custom-designed electronics and consists of seven detectors, each having an active area of 1.5m$^{2}$ plastic scintillator and wavelength shifting fibers read out by a Silicon Photomultiplier. In this contribution we review the detector design and performance, and show results from more than one year of operation of the prototype stations. During that year several thousand air shower events have been measured in coincidence with IceTop.Comment: Presented at the 36th International Cosmic Ray Conference (ICRC 2019). See arXiv:1907.11699 for all IceCube contribution

Magnetically-coupled piston pump for high-purity gas applications

Experiments based on noble elements such as gaseous or liquid argon or xenon utilize the ionization and scintillation properties of the target materials to detect radiation-induced recoils. A requirement for high light and charge yields is to reduce electronegative impurities well below the ppb level. To achieve this, the target material is continuously circulated in the gas phase through a purifier and returned to the detector. Additionally, the low backgrounds necessary dictate low-Rn-emanation rates from all components that contact the gas. Since commercial pumps often introduce electronegative impurities from lubricants on internal components or through small air leaks, and are not designed to meet the radiopurity requirements, custom-built pumps are an advantageous alternative. A new pump has been developed in Muenster in cooperation with the nEXO group at Stanford University and the nEXO/XENON group at Rensselaer Polytechnic Institute based on a magnetically-coupled piston in a hermetically sealed low-Rn-emanating vessel. This pump delivers high performance for noble gases, reaching more than 210 standard liters per minute (slpm) with argon and more than 170 slpm with xenon while maintaining a compression of up to 1.9 bar, demonstrating its capability for noble gas detectors and other applications requiring high standards of gas purity.Comment: 11 pages, 18 figure

Using Commercial Enzymes to Produce Cellulose Nanofibers from Soybean Straw

This study used commercial enzymes to isolate cellulose nanofibrils (CN) and produce sugars from chemically pretreated soybean straw (SS) (stem, leaves, and pods) by alkali (NaOH 5 or 17.5% v/v at 90°C for 1 h or at 30°C for 15 h) and bleaching (NaClO2 3.3% or H2O2 4%) pretreatments. Depending on the pretreatment applied to the soybean straw, the yield of CN varied from 6.3 to 7.5 g of CN/100 g of SS regardless of the concentration of the alkaline solution (5 or 17.5%). The CN had diameter of 15 nm, measured over 300 nm in length, and had high electrical stability (zeta potentials ranged from −20.8 to −24.5). Given the XRD patterns, the crystallinity index (CrI) of CN ranged from 45 to 68%, depending on the chemical pretreatment the starting material was submitted to. CN obtained from SS treated with NaOH 17.5% and H2O2 (CrI = 45%) displayed better thermal stability probably because a lignin-cellulose complex emerged. The soluble fraction obtained in the first step of CN production contained a large amount of reducing sugars (11.2 to 30.4 g/100 g of SS). SS seems to be a new promising industrial source to produce CN via enzymatic-mechanical treatment, leading to large amounts of reducing sugars for use in bioenergy production

Lenalidomide-based induction and maintenance in elderly newly diagnosed multiple myeloma patients: updated results of the EMN01 randomized trial

In the EMN01 trial, the addition of an alkylator (melphalan or cyclophosphamide) to lenalidomide-steroid induction has been prospectively evaluated in transplant-ineligible multiple myeloma patients. After induction, patients were randomly assigned to maintenance treatment with lenalidomide alone or with prednisone continuously. This analysis (median follow-up of 71 months) focused on maintenance treatment and on subgroup analyses according to the International Myeloma Working Group Frailty Score. 217 patients in lenalidomide-dexamethasone, 217 in melphalan-prednisone-lenalidomide and 220 in cyclophosphamide-prednisone-lenalidomide arms were evaluable. 284 (43%) patients were fit, 205 (31%) intermediate-fit and 165 (25%) frail. After induction, 402 patients were eligible for maintenance, (lenalidomide arm: 204; lenalidomide-prednisone: 198). After a median duration of maintenance of 22.0 months, progression-free survival from start of maintenance was 22.2 months with lenalidomide-prednisone vs 18.6 months with lenalidomide (HR 0.85,p=0.14), with no differences across frailty subgroups. The most frequent grade ≥3 toxicity was neutropenia (10% of lenalidomide-prednisone and 21% of lenalidomide patients; p=0.001). Grade ≥3 non-hematologic adverse events were rare (<15%). In fit patients, melphalan-prednisone-lenalidomide significantly prolonged progression-free survival compared to cyclophosphamide-prednisone-lenalidomide (HR 0.72,p=0.05) and lenalidomide-dexamethasone (HR 0.72, p=0.04). Likewise, a trend towards a better overall survival was noted for melphalan-prednisone-lenalidomide and cyclophosphamide-prednisone-lenalidomide, as compared to lenalidomide-dexamethasone. No differences were observed in intermediate-fit and frail patients. This analysis showed positive outcomes of maintenance with lenalidomide-based regimens, with a good safety profile. For the first time, we showed that fit patients benefit from a triplet full-dose regimen, while intermediate-fit and frail patients from gentler regimens. ClinicalTrials.gov registration number: NCT01093196