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The Time of Flight System of the AMS-02 Space Experiment
The Time-of-Flight (TOF) system of the AMS detector gives the fast trigger to
the read out electronics and measures velocity, direction and charge of the
crossing particles. The new version of the detector (called AMS-02) will be
installed on the International Space Station on March 2004. The fringing field
of the AMS-02 superconducting magnet is kG where the
photomultiplers (PM) are installed. In order to be able to operate with this
residual field, a new type of PM was chosen and the mechanical design was
constrained by requiring to minimize the angle between the magnetic field
vector and the PM axis. Due to strong field and to the curved light guides, the
time resolution will be ps, while the new electronics will allow
for a better charge measurement.Comment: 5 pages, 4 figures. Proc. of 7th Int. Conf. on Adv. Tech. and Part.
Phys., 15-19 October 2001,Como (Italy
Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped Zinc Oxide
Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V
ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of
the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal
annealing (RTA) treatment performed at 600 °C for different lengths of time (1 and 5 min) in an oxygen
atmosphere. Substitutional doping of Zn2+ with V3+ and V5+ ions strongly deteriorated the hexagonal
wurtzite ZnO structure of the as-grown thin films due to lattice distortion. The resulting slight
amorphization led to a poor piezoelectric response and higher resistivity. After the RTA treatment,
strong c-axis oriented VZO thin films were obtained, together with a partial conversion of the starting
V3+ ions into V5+. The improvement of the crystal structure and the stronger polarity of both V3+ – O
and V5+ – O chemical bonds, together with the corresponding easier rotation under the application of
an external electric field, positively affected the piezoelectric response and increased conductivity. This
was confirmed by closed-loop butterfly piezoelectric curves, by a maximum d33 piezoelectric coefficient
of 85 pm·V−1, and also by ferroelectric switching domains with a well-defined polarization hysteresis
curve, featuring a residual polarization of 12.5 μC∙cm−2
The AMS-02 Time of Flight System. Final Design
The AMS-02 detector is a superconducting magnetic spectrometer that will
operate on the International Space Station. The time of flight (TOF) system of
AMS-02 is composed by four scintillator planes with 8, 8, 10, 8 counters each,
read at both ends by a total of 144 phototubes. This paper describes the new
design, the expected performances, and shows preliminary results of the ion
beam test carried on at CERN on October 2002.Comment: 4 pages, 6 EPS figures. Proc. of the 28th ICRC (2003
Long-Term Safety of Anti-TNF Adalimumab in HBc Antibody-Positive Psoriatic Arthritis Patients: A Retrospective Case Series of 8 Patients
Immunosuppressive drugs commonly used in the treatment of psoriatic arthritis make patients more susceptible to viral, bacterial, and fungal infections because of their mechanism of action. They not only increase the risk of new infections but also act altering the natural course of preexisting infections. While numerous data regarding the reactivation of tuberculosis infection are available in the literature, poor information about the risk of reactivation or exacerbation of hepatitis viruses B and C infections during treatment with biologics has been reported. Furthermore, reported series with biological therapy included short periods of followup, and therefore, they are not adequate to verify the risk of reactivation in the long-term treatment. Our study evaluated patients with a history of hepatitis B and psoriatic arthritis treated with adalimumab and monitored up to six years. During the observation period, treatment was effective and well tolerated in all patients, and liver function tests and viral load levels remained unchanged
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