[en] A method for the synthesis of no-carrier-added of 7-[¹²³I]iodo-1,3-dihydro-5-(2-fluorophenyl)-1-methyl-2H-1,4-benzodiazepine-2-one with a radiochemical yield of 25-30% has been developed. This benzodiazepine was prepared by reaction of [¹²³I]iodide with the corresponding piperidyltriazene in acid medium and the reaction has been optimized for solvent, time and temperature. The triazene was synthesized by reduction of flunitrazepam to the amine, diazotisation and coupling with piperidine. Biodistribution studies of this radioligand in rats showed a maximum brain uptake of 0.35% of the injected dose at 15 min, which declines to 0.02% at 120 min. (author)

[en] The most recent measurements at Tevatron of the charge asymmetry in top-anti top quark pair production reduce the discrepancy with the Standard Model from 2? to 1.7?, and open a little window, at 95% C L, for negative contributions to the charge asymmetry beyond the S M. We update our analysis for colour octet gauge bosons or axigluons in flavour universal and flavour non-universal scenarios. We review other possible models and make an educated guess on their parameter space allowed by the new measurements. Finally, we comment on the prospects to measure the charge asymmetry at the Lhc.

[en] Liquid xenon has several attractive features, which make it suitable for applications to nuclear medicine, such as high scintillation yield and fast scintillation decay time, better than currently used crystals. Since the '90s, several attempts have been made to build Positron Emission Tomography scanners based on liquid xenon, which can be divided into two different approaches: on one hand, the detection of the ionization charge in TPCs, and, on the other one, the detection of scintillation light with photomultipliers. PETALO (Positron Emission Tof Apparatus with Liquid xenOn) is a novel concept, which combines liquid xenon scintillating cells and silicon photomultipliers for the readout. A first Monte Carlo investigation has pointed out that this technology would provide an excellent intrinsic time resolution, which makes it possible to measure the Time-Of-Flight with high efficiency. Also, the transparency of liquid xenon to UV and blue wavelengths opens the possibility of exploiting both scintillation and Cherenkov light for a high-sensitivity TOF-PET.

[en] NEXT is a high-pressure (10–15 bar) xenon Time Projection Chamber dedicated to neutrinoless double beta decay searches. NEXT-DEMO is a large prototype of the NEXT experiment, constructed to demonstrate the feasibility of the NEXT detector concept, in particular the capability of the TPC to achieve an optimal energy resolution at the Xe Q_ββ energy (2.458 MeV). It has been operating at IFIC, in Valencia, for one year and a half and a number of results has been achieved. Recently, the reflector panels of the prototype have been coated with a wavelength shifter (TPB), in order to improve light collection. We have obtained an energy resolution of 2.3% FWHM at 511 keV, using Na-22 radioactive sources, corresponding to 1% FWHM once extrapolated to Q_ββ.

[en] In this paper we use detailed Monte Carlo simulations to demonstrate that liquid xenon (LXe) can be used to build a Cherenkov-based TOF-PET, with an intrinsic coincidence resolving time (CRT) in the vicinity of 10 ps. This extraordinary performance is due to three facts: a) the abundant emission of Cherenkov photons by liquid xenon; b) the fact that LXe is transparent to Cherenkov light; and c) the fact that the fastest photons in LXe have wavelengths higher than 300 nm, therefore making it possible to separate the detection of scintillation and Cherenkov light. The CRT in a Cherenkov LXe TOF-PET detector is, therefore, dominated by the resolution (time jitter) introduced by the photosensors and the electronics. However, we show that for sufficiently fast photosensors (e.g, an overall 40 ps jitter, which can be achieved by current micro-channel plate photomultipliers) the overall CRT varies between 30 and 55 ps, depending on the detection efficiency. This is still one order of magnitude better than commercial CRT devices and improves by a factor 3 the best CRT obtained with small laboratory prototypes.

[en] The NEXT experiment aims to observe the neutrinoless double beta decay of "1"3"6Xe in a high-pressure xenon gas TPC using electroluminescence (EL) to amplify the signal from ionization. One of the main advantages of this technology is the possibility to reconstruct the topology of events with energies close to Q_β_β. This paper presents the first demonstration that the topology provides extra handles to reject background events using data obtained with the NEXT-DEMO prototype. Single electrons resulting from the interactions of "2"2Na 1275 keV gammas and electron-positron pairs produced by conversions of gammas from the "2"2"8Th decay chain were used to represent the background and the signal in a double beta decay. These data were used to develop algorithms for the reconstruction of tracks and the identification of the energy deposited at the end-points, providing an extra background rejection factor of 24.3±1.4 (stat.)%, while maintaining an efficiency of 66.7±1.% for signal events.

[en] NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will search for the neutrinoless double beta (0νββ) decay of "1"3"6Xe. The detector possesses two features of great value for 0νββ searches: energy resolution better than 1% FWHM at the Q value of "1"3"6Xe and track reconstruction for the discrimination of signal and background events. This combination results in excellent sensitivity, as discussed in this paper. Material-screening measurements and a detailed Monte Carlo detector simulation predict a background rate for NEXT-100 of at most 4×10"−"4 counts keV"−"1 kg"−"1 yr"−"1. Accordingly, the detector will reach a sensitivity to the 0νββ-decay half-life of 2.8×10"2"5 years (90% CL) for an exposure of 100 kg⋅year, or 6.0×10"2"5 years after a run of 3 effective years.

No abstract available

[en] We report on the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead, as compared to other superconducting metals. The concept, mentioned in a previous paper, follows the attractive approach of all niobium superconducting RF-gun as it has been proposed by the BNL group. Measured values of quantum efficiency for lead at various photon energies, analysis of recombination time of photon-broken Cooper pairs for lead and niobium, and preliminary cold test results are discussed in this paper

[en] The cerebral distribution of ^99mTc-labeled d, 1, hexamethyl-propylene-amine-oxime (^99mTc-HMPAO) as a function of rCBF and time was examined in rats and in man. The results of this study confirm that ^99mTc-HMPAO is distributed in brain in proportion to rCBF. However, the rapid systemic breakdown of the tracer in blood results in considerable difficulties in the assessment of the arterial concentration of the parent compound; incomplete extraction of ^99mTc-HMPAO from blood to brain and significant efflux from brain represent further limitations in the use of this tracer for quantification of rCFB. Despite these limitations ^99mTc-HMPAO is of potential interest for a qualitative assessment of rCBF in specific clinical conditions. (orig.)