Measurement of the neutron lifetime using a gravitational trap and a low-temperature Fomblin coating

We present a new value for the neutron lifetime of 878.5 +- 0.7 stat. +- 0.3 syst. This result differs from the world average value (885.7 +- 0.8 s) by 6.5 standard deviations and by 5.6 standard deviations from the previous most precise result. However, this new value for the neutron lifetime together with a beta-asymmetry in neutron decay, Ao, of -0.1189(7) is in a good agreement with the Standard Model.Comment: 11 pages, 9 figures; extended content with some correction

Neutron lifetime measurements using gravitationally trapped ultracold neutrons

Our experiment using gravitationally trapped ultracold neutrons (UCN) to measure the neutron lifetime is reviewed. Ultracold neutrons were trapped in a material bottle covered with perfluoropolyether. The neutron lifetime was deduced from comparison of UCN losses in the traps with different surface-to-volume ratios. The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. In this experiment, the UCN storage time is brought closer to the neutron lifetime than in any experiments before:the probability of UCN losses from the trap was only 1% of that for neutron beta decay. The neutron lifetime obtained,878.5+/-0.7stat+/-0.3sys s, is the most accurate experimental measurement to date.Comment: 38 pages, 19 figures,changed conten

New Neutron Lifetime Measurements with the Big Gravitational Trap and Review of Neutron Lifetime Data

Neutron lifetime is one of the most important physical constants which determines parameters of the weak interaction and predictions of primordial nucleosynthesis theory. In our experiment we measure the storage time of UCN in the material trap coated with a hydrogen-free fluorine-containing polymer (Fomblin grease UT-18). The stability of this coating to multiple thermal cycles between 80 K and 300 K was tested. The achieved storage time is only 1.5% less than free neutron lifetime. Using additional surface, which can be plunged into the trap to change the collision frequency of UCN with walls, we calculate free neutron lifetime by extrapolation to zero collision frequency. The result of the measurements with this new experimental setup i

Experimental search for long-range forces in neutron scattering via a gravitational spectrometer

© 2014 American Physical Society, https://dx.doi.org/10.1103/physrevc.89.044002In this work we introduce a method of measuring low-energy scattering cross section with a gravitational spectrometer. In this method we add atoms (i.e., He) to the gravitational spectrometer filled with a target gas of ultracold neutrons (UCN). We search for long-range forces between atoms and UCN by measuring transfer of a small recoil energy similar to 10(-7) eV using the gravitational spectrometer. As a result of this search we set new constraints on the strength of long-range forces within the range of the effective radius of interaction of 10(-7)-10(-4) cm.Russian Foundation for Basic Research (Projects No. 08-02-01052a, No. 10-02-00217a, and No. 10-02-00224a)Ministry of Education and Science of the Russian Federation (Contracts No. 02.740.11.0532 and No. 14.740.11.0083

Ис­пользование пероксида водорода выдыхаемого воздуха для оценки эффективности терапии бронхиальной астмы

Exhaled hydrogen peroxide is a marker of airway inflammation. However, its utility for monitoring of asth­ma is still uncertain. The aim of this study was to assess the effect of short-acting β2-agonists and inhaled steroids on the hydrogen peroxide (H202) concentration in expired breath condensate in asthmatic patients. Fifteen patients with moderate atopic asthma were treated with salbutamol as required for 2 weeks followed 12-week treatment with budesonide (Pulmicort Turbuhaler, 400 meg daily). The exhaled H202 concentration as measured using a colorimetric assay (Gallati&Pracht, 1985). FEV1 was assessed using dry spirometer. Airway hyperresponsiveness was considered as a provocative concentration of inhaled histamine causing the 20%-fall in FEV1 (PD20).The H202 baseline level in the asthmatic patients (0.19±0.03 μ‎M) was elevated compared to healthy sub­jects (0.028±0.003, p<0.001). The exhaled H202 concentration did not change during the treatment with salbutamol but it was diminished by Pulmicort Turbuhaler. This was associated with significant improvement in clinical symptom score, FEV1 and PD20 in asthma patients.We conclude that the short-acting β2-agonists do not influence the H202 concentration in the exhaled air condensate of the asthma patients but the inhaled steroids decrease it. This may reflect different anti-inflam­matory activities of these medications.Целью настоящей работы явилось изучение влияния β2-агонистов и ингаляционных стероидов (ИГКС) на концентрацию пероксида водорода (Н2O2) в конденсате выдыхаемого воздуха (КВВ) у больных бронхиальной астмой (БА). Под наблюдением находилось 15 больных атопической БА средней тяжести течения, которые в течение 2 нед получали сальбутамол в режиме "по требованию", а затем в течение 12 нед получали будесонид (пульмикорт турбухалер в дозе 400 мкг/сут). Концентрацию Н2O2 в КВВ изучали спектрофотометрическим методом ("Gallati&Pracht”, 1985). Бронхиальную проходимость (ОФВ1) изучали методом спирометрии. Для оценки гиперреактивности бронхов (ПД20) использовали бронхопровокационный тест с гистамином.Уровень Н2O2 в процессе лечения сальбутамолом (0,19±0,03 мкМ) существенно не изменялся по сравнению с исходным (0,19±0,04 мкМ), а при назначении будесонида достоверно снижался (0,038±0,005). Изменение Н2O2 происходило параллельно с улучшением клинического состояния больных, увеличением ОФВ1 и снижением ПД20.Таким образом, β2-агонисты не влияют, а ИГКС снижают концентрацию Н2O2 в КВВ у больных БА, что, вероятно, отражает их различное влияние на активность воспалительного процесса. Это подтверждает возможность использования Н2O2 в качестве маркера воспаления в дыхательных путях у пациентов с астмой