Radiation Hardness and Linearity Studies of CVD Diamonds

We report on the behavior of CVD diamonds under intense electromagnetic radiation and on the response of the detector to high density of deposited energy. Diamonds have been found to remain unaffected after doses of 10 MGy of MeV-range photons and the diamond response to energy depositions of up to 250 GeV/cm^3 has been found to be linear to better than 2 %. These observations make diamond an attractive detector material for a calorimeter in the very forward region of the detector proposed for TESLA.Comment: 4 pages, 5 figures; Proceeding for the topical Seminar on Innovative Particle and Radiation Detectors Siena, 21-24 October 2002; to appear in Nucl.Phys. B (Proceedings Supplement

Electromagnetic Radiation Hardness of Diamond Detectors

The behavior of artificially grown CVD diamond films under intense electromagnetic radiation has been studied. The properties of irradiated diamond samples have been investigated using the method of thermally stimulated current and by studying their charge collection properties. Diamonds have been found to remain unaffected after doses of 6.8 MGy of 10 keV photons and 10 MGy of MeV-range photons. This observation makes diamond an attractive detector material for a calorimeter in the very forward region of the proposed TESLA detector.Comment: 19 pages, 9 figure

Characterization and Modeling of Non-Uniform Charge Collection in CVD Diamond Pixel Detectors

A pixel detector with a CVD diamond sensor has been studied in a 180 GeV/c pion beam. The charge collection properties of the diamond sensor were studied as a function of the track position, which was measured with a silicon microstrip telescope. Non-uniformities were observed on a length scale comparable to the diamond crystallites size. In some regions of the sensor, the charge drift appears to have a component parallel to the sensor surface (i.e., normal to the applied electric field) resulting in systematic residuals between the track position and the hits position as large as 40 $\mu$m. A numerical simulation of the charge drift in polycrystalline diamond was developed to compute the signal induced on the electrodes by the electrons and holes released by the passing particles. The simulation takes into account the crystallite structure, non-uniform trapping across the sensor, diffusion and polarization effects. It is in qualitative agreement with the data. Additional lateral electric field components result from the non-uniform trapping of charges in the bulk. These provide a good explanation for the large residuals observed.Comment: Accepted by Nucl. Instr. and Met

Possible Single Resonant Production of the Fourth Generation Charged Leptons at γe\gamma e Colliders

Single resonant productions of the fourth standard model generation charged lepton via anomalous interactions at gamma e colliders based on future linear e^+ e^- colliders with 500 GeV and 1 TeV center of mass energies are studied. Signatures of $\gamma e\to \ell_4\to e\gamma$ and $\gamma e\to \ell_4\to eZ$ anomalous processes followed by the hadronic and leptonic decay of the Z boson and corresponding standard model backgrounds are discussed in details. The lowest necessary luminosities to observe these processes and the achievable values of the anomalous coupling strengths are determined.Comment: 9 pages, 6 figures, 4 table

Human hypocretin and melanin-concentrating hormone levels are linked to emotion and social interaction.

The neurochemical changes underlying human emotions and social behaviour are largely unknown. Here we report on the changes in the levels of two hypothalamic neuropeptides, hypocretin-1 and melanin-concentrating hormone, measured in the human amygdala. We show that hypocretin-1 levels are maximal during positive emotion, social interaction and anger, behaviours that induce cataplexy in human narcoleptics. In contrast, melanin-concentrating hormone levels are minimal during social interaction, but are increased after eating. Both peptides are at minimal levels during periods of postoperative pain despite high levels of arousal. Melanin-concentrating hormone levels increase at sleep onset, consistent with a role in sleep induction, whereas hypocretin-1 levels increase at wake onset, consistent with a role in wake induction. Levels of these two peptides in humans are not simply linked to arousal, but rather to specific emotions and state transitions. Other arousal systems may be similarly emotionally specialized

Description of a new species of Heligmonina Baylis, 1928 (Nematoda: Heligmonellidae) a parasite of Mastomys Natalensis (Rodentia: Muridae) from Swaziland and new data on the synlophe of Heligmonina Chabaudi (Desset, 1966)

A new species of heligmosomoid nematode belonging to the subfamily Nippostrongylinae Durette-Desset, 1970 is described: Heligmonina wakelini n. sp., a parasite from the small intestine of the commensal rodent Mastomys natalensis (Smith, 1834) from Swaziland. It differs from the most closely related species H. boomkeri Durette-Desset & Digiani, 2005 by the number of the cuticular ridges in the female synlophe (10 vs 12), the width of the left ala, larger than the body diameter in the male, and the inclination of the axis of orientation of the ridges in both sexes (53° vs 70°). New morphological data (head and synlophe) on Heligmonina chabaudi (Desset, 1964), also a parasite of Mastomys natalensis in the Republic of Congo, are provided in order to compare with the new species.Facultad de Ciencias Naturales y Muse

Description of a new species of Heligmonina Baylis, 1928 (Nematoda: Heligmonellidae) a parasite of Mastomys Natalensis (Rodentia: Muridae) from Swaziland and new data on the synlophe of Heligmonina Chabaudi (Desset, 1966)

A new species of heligmosomoid nematode belonging to the subfamily Nippostrongylinae Durette-Desset, 1970 is described: Heligmonina wakelini n. sp., a parasite from the small intestine of the commensal rodent Mastomys natalensis (Smith, 1834) from Swaziland. It differs from the most closely related species H. boomkeri Durette-Desset & Digiani, 2005 by the number of the cuticular ridges in the female synlophe (10 vs 12), the width of the left ala, larger than the body diameter in the male, and the inclination of the axis of orientation of the ridges in both sexes (53° vs 70°). New morphological data (head and synlophe) on Heligmonina chabaudi (Desset, 1964), also a parasite of Mastomys natalensis in the Republic of Congo, are provided in order to compare with the new species.Facultad de Ciencias Naturales y Muse