SiPMs coated with TPB : coating protocol and characterization for NEXT

Silicon photomultipliers (SiPM) are the photon detectors chosen for the tracking readout in NEXT, a neutrinoless {\beta}{\beta} decay experiment which uses a high pressure gaseous xenon time projection chamber (TPC). The reconstruction of event track and topology in this gaseous detector is a key handle for background rejection. Among the commercially available sensors that can be used for tracking, SiPMs offer important advantages, mainly high gain, ruggedness, cost-effectiveness and radio-purity. Their main drawback, however, is their non sensitivity in the emission spectrum of the xenon scintillation (peak at 175 nm). This is overcome by coating these sensors with the organic wavelength shifter tetraphenyl butadienne (TPB). In this paper we describe the protocol developed for coating the SiPMs with TPB and the measurements performed for characterizing the coatings as well as the performance of the coated sensors in the UV-VUV range.Comment: Submitted to the Journal of Instrumentation on december 26th 201

Checkrein Deformity of the Hallux and Second Toe after Soft-Tissue Injury

We report the case of a patient who developed a checkrein deformity of the hallux and of the second toe following a direct soft tissue trauma to his right leg, with no associated fracture. This dynamic deformity caused the patient significant trouble walking and prevented him from playing any sport as in the stance phase of gait the toes were forced into maximum plantar flexion and ended up trapped under the foot. An MRI study did not show any bone injury or tendinous tethering. So the cause could be a subclinical compartment syndrome. Treatment consisted of a z-plasty and application of a pulvertaft suture to the flexor hallucis longus. Following a short rehabilitation program (2 weeks), the patient made a full recovery