SELEX RICH Performance and Physics Results

SELEX took data in the 1996/7 Fixed Target Run at Fermilab. The excellent performance parameters of the SELEX RICH Detector had direct influence on the quality of the obtained physics results.Comment: Contributed talk at the Fourth Workshop on RICH Detectors, June 5-10, 2002, Pylos, Greece. Accepted for publication in NIM

Growth of nano dots on the grazing incidence mirror surface under FEL irradiation Analytic approach to modeling

Simple analytic equation is deduced to explain new physical phenomenon detected experimentally growth of nano dots 40 55 nm diameter, 8 13 nm height, 9.4 dots amp; 956;m2 surface density on the grazing incidence mirror surface under the three years irradiation by the free electron laser FLASH 5 45 nm wavelength, 3 degrees grazing incidence angle . The growth model is based on the assumption that the growth of nano dots is caused by polymerization of incoming hydrocarbon molecules under the action of incident photons directly or photoelectrons knocked out from a mirror surface. The key feature of our approach consists in that we take into account the radiation intensity variation nearby a mirror surface in an explicit form, because the polymerization probability is proportional to it. We demonstrate that the simple analytic approach allows to explain all phenomena observed in experiment and to predict new effects. In particular, we show that the nano dots growth depends crucially on the grazing angle of incoming beam and its intensity growth of nano dots is observed in the limited from above and below intervals of the grazing angle and the radiation intensity. Decrease in the grazing angle by 1 degree only from 3 to 2 degree may result in a strong suppression of nanodots growth and their total disappearing. Similarly, decrease in the radiation intensity by several times replacement of free electron laser by synchrotron results also in disappearing of nano dots growt

Послеоперационное обезболивание при тотальном эндопротезировании коленного сустава: сравнительный анализ эффективности современных методик

The objective of the study was to evaluate the effectiveness and safety of high-volume local infiltration and epidural analgesic techniques after primary total knee arthroplasty versus standard systemic multimodal analgesia in the context of the postoperative analgesia protocols.Materials and Methods. A single-center randomized comparative study included 84 patients who, from august 2017 to august 2018, underwent a primary total knee arthroplasty. Depending on the method of postoperative analgesia, we randomized patients into 3 groups. Group A consisted of 32 patients who received intraoperative infiltration of periarticular tissues with 0.2% solution of ropivacaine in combination with adrenaline and subsequent bolus injection of a local anesthetic solution via a catheter inserted into the wound. Group B included patients who received epidural analgesia with a constant infusion of a 0.2% solution of ropivacaine (n = 28). In patients of group C, neither regional nor local analgesia techniques were used for postoperative analgesia (n = 24). All patients received standard systemic multimodal analgesia using nonsteroidal anti-inflammatory drugs and tramadol. The pain intensity was measured by vas when the patient was motionless, and during knee flexion (before surgery, after surgery on resolution of motor block and during the initial postoperative 24 h), side-effects were recorded.Results. The patients of Group C, during knee flexion in the postoperative period, reported the highest pain scores (6 (5; 8) during the initial postoperative 12 h and 6 (5; 6) during the initial postoperative 24 h). Severe pain, resistant to therapy and requiring the administration of narcotic analgesics (morphine 1.0 mg), was noted in 5 (15.6%) patients in group A and in 10 (41.6%) in group C, in contrast to patients of group B, where no pain was recorded in any patient, p = 0.056, p = 0.037 and p0.0001. Hypotension was observed only in group B in 6 (22%) patients. Intra-articular and other infectious complications among all patients were not recorded.Conclusion. High-volume local infiltration analgesia as a modality of postoperative analgesia is not inferior in the effectiveness to the epidural analgesia, does not require strict monitoring and is accompanied by a lower incidence of side-effects and complications, which can make it the procedure of choice in multimodal analgesia schemes for total knee arthroplasty.Цель исследования — оценить эффективность и безопасность местной высокообъемной инфильтрационной и эпидуральной методик аналгезии при проведении первичного тотального эндопротезирования коленного сустава в сравнении со стандартной системной мультимодальной аналгезией в рамках протоколов послеоперационного обезболивания.Материал и методы. Проведено одноцентровое рандомизированное сравнительное исследование, в которое вошли 84 пациента, с августа 2017 г. По август 2018 г. Перенесшие первичное тотальное эндопротезирование коленного сустава. В зависимости от методики послеоперационного обезболивания пациенты были рандомизированы на 3 группы. В группу А вошли 32 пациента, которым была выполнена интраоперационная инфильтрация периартикулярных тканей 0,2% раствором ропивакаина в сочетании с адреналином и последующим болюсным введением раствора местного анестетика через установленный в рану катетер. В группу В были включены пациенты, которым проводилась эпидуральная аналгезия постоянной инфузией 0,2% раствора ропивакаина (n = 28). У пациентов группы С для послеоперационного обезболивания не применялись ни регионарные, ни местные методики аналгезии (n = 24). Всем пациентам проводилась стандартная многокомпонентная системная аналгезия с использованием нестероидных противовоспалительных средств и трамадола. Регистрировалась выраженность болевого синдрома по 10-балльной визуально-аналоговой шкале в покое и при сгибании коленного сустава (до операции, после операции при разрешении моторного блока и в 1-е послеоперационные сутки), фиксировались побочные и нежелательные реакции.Результаты. Наибольшая выраженность болевого синдрома при сгибании коленного сустава в послеоперационном периоде отмечена у пациентов группы С (6 (5;8) в день операции и 6 (5;6) баллов в 1-е послеоперационные сутки). Сильная боль, резистентная к проводимой терапии и потребовавшая введения наркотических аналгетиков (морфин 1,0 мг), была отмечена у 5 (15,6%) пациентов в группе А и у 10 (41,6%) в группе С, в отличие от пациентов группы В, где выраженного болевого синдрома не зафиксировано ни у одного пациента, р = 0,056, р = 0,037 и р0,0001. Гипотензия отмечена только в группе В у 6 (22%) пациентов. Внутрисуставных и иных инфекционных осложнений во всех группах всех пациентов зафиксировано не было.Заключение. Местная высокообъемная инфильтрационная аналгезия не уступает по эффективности послеоперационного обезболивания эпидуральной аналгезии, не требует проведения жесткого мониторинга и сопровождается меньшей частотой побочных реакций и осложнений, что может сделать ее «процедурой выбора» в схеме мультимодальной аналгезии при проведении тотального эндопротезирования коленного сустава.

Effect of the surface roughness on X ray absorption by mirrors operating at extremely small grazing angles

This study theoretically analyzes an increase in X ray absorption by a grazing incidence mirror due to its surface roughness. We demonstrate that the increase in absorption can be several hundred times larger than predicted by the Nevot Croce formula. As a result, absorption enhances by several times compared to a perfectly smooth mirror despite the extremely small grazing angle of an incident X ray beam a fraction of the critical angle of the total external reflection and the high quality of the reflecting surface the roughness height was 0.5 nm in modeling . The main contribution to the absorption increase was dictated by the mid scale roughness waviness of the virgin substrate surface, whose quality thus defines an absorption enhancement. The approach was applied to the analysis of two real mirrors used in a synchrotron BESSY I and a European X ray free electron laser XFEL beamline. The modern surface finishing technology of elastic emission machining provides extremely low substrate waviness, guaranteeing the negligible effect of the surface roughness on the absorption increas

Current noise in long diffusive SNS junctions in the incoherent MAR regime

Spectral density of current fluctuations at zero frequency is calculated for a long diffusive SNS junction with low-resistive interfaces. At low temperature, T << Delta, the subgap shot noise approaches linear voltage dependence, S=(2/ 3R)(eV + 2Delta), which is the sum of the shot noise of the normal conductor and voltage independent excess noise. This result can also be interpreted as the 1/3-suppressed Poisson noise for the effective charge q = e(1+2Delta/eV) transferred by incoherent multiple Andreev reflections (MAR). At higher temperatures, anomalies of the current noise develop at the gap subharmonics, eV = 2Delta/n. The crossover to the hot electron regime from the MAR regime is analyzed in the limit of small applied voltages.Comment: improved version, to be published in Phys. Rev.

Search for the decay K+ to pi+ gamma gamma in the pi+ momentum region P>213 MeV/c

We have searched for the K+ to pi+ gamma gamma decay in the kinematic region with pi+ momentum close to the end point. No events were observed, and the 90% confidence-level upper limit on the partial branching ratio was obtained, B(K+ to pi+ gamma gamma, P>213 MeV/c) < 8.3 x 10-9 under the assumption of chiral perturbation theory including next-to-leading order ``unitarity'' corrections. The same data were used to determine an upper limit on the K+ to pi+ gamma branching ratio of 2.3 x 10-9 at the 90% confidence level.Comment: 15 pages, 3 figures; no change in the results, accepted for publication in Physics Letters

Measurement of the Ds lifetime

We report precise measurement of the Ds meson lifetime. The data were taken by the SELEX experiment (E781) spectrometer using 600 GeV/c Sigma-, pi- and p beams. The measurement has been done using 918 reconstructed Ds. The lifetime of the Ds is measured to be 472.5 +- 17.2 +- 6.6 fs, using K*(892)0K+- and phi pi+- decay modes. The lifetime ratio of Ds to D0 is 1.145+-0.049.Comment: 5 pages, 2 figures submitted to Phys. Lett.

Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical method to determine significance of observation. Submitted to PL

Hadronic Production of Lambda_c from 600 GeV/c pion, sigma and proton beams

We present data from Fermilab experiment E781 (SELEX) on the hadroproduction asymmetry for anti-Lambda_c compared to Lambda_c+ as a function of xF and pt2 distributions for Lambda_c+. These data were measured in the same apparatus using incident pi-, sigma- beams at 600 GeV/c and proton beam at 540 GeV/c. The asymmetry is studied as a function of xF. In the forward hemisphere with xF >= 0.2 both baryon beams exhibit very strong preference for producing charm baryons rather than charm antibaryons, while the pion beam asymmetry is much smaller. In this energy regime the results show that beam fragments play a major role in the kinematics of Lambda_c formation, as suggested by the leading quark picture.Comment: 6 pages, 5 figures (postscript), RevTeX, submitted to Phy. Rev. Let