Un système d'acquisition de données pour l'analyse en ligne des photographies de grandes chambres à bulles

Ce travail présente le système d'analyse des clichés de grandes chambres à bulles telles que Gargamelle et BEBC, réalisé au Groupe de Chambre à Bulles à Liquide Lourd à l'aide d'appareils de projection mis en ligne sur ordinateur CDC 1700. Ce travail présente les caractéristiques générales de ces appareils ainsi que celles de l'ordinateur et développe la conception et les fonctions des programmes d'analyse des photographies : prémesures, mesures et gestion des données. L'ensemble du système d'acquisition de données fonctionne dans un contexte de multiprogrammation en temps réel

Possible background reductions in double beta decay experiments

The background induced by radioactive impurities of $^{208}\rm Tl$ and $^{214}\rm Bi$ in the source of the double beta experiment NEMO-3 has been investigated. New methods of data analysis which decrease the background from the above mentioned contamination are identified. The techniques can also be applied to other double beta decay experiments capable of measuring independently the energies of the two electrons.Comment: 15 pages, 13 figures, accepted in the Nuclear Instruments and Methods

Technical design and performance of the NEMO3 detector

The development of the NEMO3 detector, which is now running in the Frejus Underground Laboratory (L.S.M. Laboratoire Souterrain de Modane), was begun more than ten years ago. The NEMO3 detector uses a tracking-calorimeter technique in order to investigate double beta decay processes for several isotopes. The technical description of the detector is followed by the presentation of its performance.Comment: Preprint submitted to Nucl. Instrum. Methods A Corresponding author: Corinne Augier ([email protected]

Limits on different Majoron decay modes of 100^{100}Mo and 82^{82}Se for neutrinoless double beta decays in the NEMO-3 experiment

The NEMO-3 tracking detector is located in the Fr\'ejus Underground Laboratory. It was designed to study double beta decay in a number of different isotopes. Presented here are the experimental half-life limits on the double beta decay process for the isotopes $^{100}$Mo and $^{82}$Se for different Majoron emission modes and limits on the effective neutrino-Majoron coupling constants. In particular, new limits on "ordinary" Majoron (spectral index 1) decay of $^{100}$Mo ($T_{1/2} > 2.7\cdot10^{22}$ y) and $^{82}$Se ($T_{1/2} > 1.5\cdot10^{22}$ y) have been obtained. Corresponding bounds on the Majoron-neutrino coupling constant are $< (0.4-1.9) \cdot 10^{-4}$ and $< (0.66-1.7) \cdot 10^{-4}$.Comment: 23 pages includind 4 figures, to be published in Nuclear Physics

De nouvelles sondes peropératoires à l'essai pour la chirurgie du ganglion sentinelle

Pour accroître les performances de la procédure sentinelle dans la chirurgie des tumeurs lymphophiles (mammaires, vulvaires, mélanomes...), plusieurs équipes travaillent actuellement sur l'optimisation des sondes peropératoires pour la recherche des ganglions radiomarqués. La détection des ganglions sentinelles repose sur l'utilisation de matériaux permettant de classer les sondes en deux catégories : les sondes à semi-conducteurs et les sondes à cristaux scintillants. Toutes deux convertissent les rayons gamma émis par le technétium 99m ($^{99m}$Tc) retenu par le ganglion sentinelle en électrons par effet photoélectrique et en extraient un signal exploitable. La qualité du blindage, la collimation et la production du signal électrique varient pour chaque sonde. La performance d'une sonde est déterminée par son pouvoir séparateur, sa sensibilité et sa maniabilité

Study of 4 inorganic scintillating crystals for an operative gamma probe in radioguided surgery

In case of lymphatic cancers, the sentinel lymph node technique is performed using a gamma probe for intraoperative radioguided surgery. The inorganic scintillating crystal gamma probe developed at IPHC was equipped with 4 fast decay time inorganic scintillators: YAP, LYSO, LaCl3 and LaBr3. Energy resolutions are compared experimentally with single photon radioisotopes for small crystal cylinders (4 mm diameter, 12 mm length). The 6.1% measured energy resolution at 511 keV demonstrates the great advantage to use the high photon yield LaBr3 crystal for detection of γ-ray coming from positron annihilation using β+ radiomarked molecule

AMISSA: a multimodality imaging system for small animal

International audienc

Development of a high resolution SPECT system dedicated to small animal imaging

International audienceThe interest of small animal imaging has been primarily due to the recent advances in genetics with the need to perform longitudinal studies on mice or rat. Recent work has shown that single photon emission computed tomography (SPECT) imaging of small animals can provide high spatial resolution with a high sensitivity where the addition of an X-ray CT system provides the lack of anatomical structures. In our group, we are developing a multi modality system combining X-ray, SPECT and PET imaging system. In this paper, we discuss the development of the SPECT component The key features of the system are i) four individual cameras arranged around the animal, ii) one pinhole aperture and 5 detector modules per camera, iii) a 28 mm focal length, and iii) pixellated scintillator arrays of 2.3×2.3×28 mm3 VAP:Ce pixels coupled to 8×8 multi anode PMT. With the pinhole configuration, the axial field of view strongly depends on the axial size of the PMT which is 18.4 mm. In order to increase this field of view, an hybrid collimator made of parallel strip of tungsten is designed. This collimator leads to parallel collimation in the axial direction and pinhole collimation in the transverse direction. The intrinsic resolution of the system is measured to be 1.5 mm in both directions leading to a 1 mm spatial resolution in the center of the field of view using a 0.5 mm diameter pinhole aperture. The predicted absolute detection efficiency of the system is 34.9 cps/MBq and 12.9 cps/MBq for the pinhole and the hybrid collimation. As a conclusion, we propose a modular SPECT system with high spatial resolution combined with high sensitivity