Trapping in irradiated p-on-n silicon sensors at fluences anticipated at the HL-LHC outer tracker

The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 $\mu$m thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to $3 \cdot 10^{15}$ neq/cm$^2$. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggests an improved tracker performance over initial expectations

Evaluation and Management of Vaginitis

OBJECTIVE: To evaluate recent advances in our understanding of the clinical relevance, diagnosis, and treatment of vaginal infections, and to determine an efficient and effective method of evaluating this clinical problem in the outpatient setting. DATA SOURCES: Relevant papers on vaginitis limited to the English language obtained through a MEDLINE search for the years 1985 to 1997 were reviewed. DATA SYNTHESIS: Techniques that enable the identification of the various strains of candida have helped lead to a better understanding of the mechanisms of recurrent candida infection. From this information a rationale for the treatment of recurrent disease can be developed. Bacterial vaginosis has been associated with complications, including upper genital tract infection, preterm delivery, and wound infection. Women undergoing pelvic surgery, procedures in pregnancy, or pregnant women at risk of preterm delivery should be evaluated for bacterial vaginosis to decrease the rate of complications associated with this condition. New, more standardized criteria for the diagnosis of bacterial vaginosis may improve diagnostic consistency among clinicians and comparability of study results. Use of topical therapies in the treatment of bacterial vaginosis are effective and associated with fewer side effects than systemic medication. Trichomonas vaginalis, although decreasing in incidence, has been associated with upper genital tract infection. Therapy of T. vaginalis infection has been complicated by an increasing incidence of resistance to metronidazole. CONCLUSIONS: Vaginitis is a common medical problem in women that is associated with significant morbidity and previously unrecognized complications. Research in recent years has improved diagnostic tools as well as treatment modalities for all forms of vaginitis

Trapping in proton irradiated p(+)-n-n(+) silicon sensors at fluences anticipated at the HL-LHC outer tracker

The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 μm thick n-type silicon sensors are irradiated with protons of 15 2 different energies to fluences of up to 3 · 10 neq/cm . Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggest an improved tracker performance over initial expectations

Impact of low-dose electron irradiation on n+p silicon strip sensors

AbstractThe response of n+p silicon strip sensors to electrons from a 90Sr source was measured using a multi-channel read-out system with 25ns sampling time. The measurements were performed over a period of several weeks, during which the operating conditions were varied. The sensors were fabricated by Hamamatsu Photonics on 200μm thick float-zone and magnetic-Czochralski silicon. Their pitch was 80μm, and both p-stop and p-spray isolation of the n+ strips were studied. The electrons from the 90Sr source were collimated to a spot with a full-width-at-half-maximum of 2mm at the sensor surface, and the dose rate in the SiO2 at the maximum was about 50Gy(SiO2)/d. After only a few hours of making measurements, significant changes in charge collection and charge sharing were observed. Annealing studies, with temperatures up to 80°C and annealing times of 18h showed that the changes can only be partially annealed. The observations can be qualitatively explained by the increase of the positive oxide-charge density due to the ionization of the SiO2 by the radiation from the β source. TCAD simulations of the electric field in the sensor for different oxide-charge densities and different boundary conditions at the sensor surface support this explanation. The relevance of the measurements for the design of n+p strip sensors is discussed