8,034 research outputs found
Nuclear Track Detectors for Environmental Studies and Radiation Monitoring
Several improvements were made for Nuclear Track Detectors (NTDs) used for
environmental studies and for particle searches. A new method was used to
determine the bulk etch rate of CR39 and Makrofol NTDs. It is based on the
simultaneous measurement of the diameter and of the height of etch-pit cones
caused by relativistic heavy ions (158 A GeV Pb(82+) and In(49+) ions) and
their fragments. The use of alcohol in the etching solution improves the
surface quality of NTDs and it raises their thresholds. The detectors were used
for the determination of nuclear fragmentation cross sections of Iron and
Silicon ions of 1.0 and 0.41 GeV/nucleon. These measurements are important for
the determination of doses in hadron therapy and for doses received by
astronauts. The detectors were also used in the search of massive particles in
the cosmic radiation, for the determination of the mass spectrum of cosmic rays
and for the evaluation of Po(210) alpha decay and of natural radon
concentrations.Comment: 7 pages, 5 EPS figures. Presented at the 10th Topical Seminar on
Innovative Particle and Radiation Detectors, 1-5 October 2006, Siena, Ital
The surgical management of locally advanced well-differentiated thyroid carcinoma. Changes over the years according to the AJCC 8th edition Cancer Staging Manual
Background: Well-differentiated thyroid carcinoma is defined as locally advanced in the presence of an extra thyroid extension, e.g., when the surrounding structures such as the trachea, larynx, esophagus and main blood vessels are invaded by cancer. The 8th edition AJCC Cancer Staging Manual states that this is the main characteristic to evaluate for the staging and consequently for the prognosis in patients over 55 years old. Main body: Distinguishing different forms of locally advanced thyroid cancer is essential, and the various anatomical structures and the clinical and therapeutic consequences must be taken into account. An accurate diagnosis of the organs invaded by thyroid cancer is necessary for the planning of surgical treatment, and both aspects are crucial to improving the patients' survival. Patients affected by thyroid cancer with extra thyroid extension have a poor prognosis and the removal of the entire neoplasm represents a key factor for better disease-free survival. Conclusions: We discuss the changes introduced by the 8th edition AJCC Cancer Staging Manual, in terms of the diagnostic and surgical management of extra thyroid extension, in patients affected by papillary and follicular thyroid cancer
Meaurement of Cosmic Ray elemental composition from the CAKE balloon experiment
CAKE (Cosmic Abundances below Knee Energies) was a prototype balloon
experiment for the determination of the charge spectra and of abundances of the
primary cosmic-rays (CR) with Z10. It was a passive instrument made of
layers of CR39 and Lexan nuclear track detectors; it had a geometric acceptance
of 0.7 msr for Fe nuclei. Here, the scanning and analysis strategies,
the algorithms used for the off-line filtering and for the tracking in
automated mode of the primary cosmic rays are presented, together with the
resulting CR charge distribution and their abundances.Comment: 5 pages, 8 figure
Bulk Etch Rate Measurements and Calibrations of Plastic Nuclear Track Detectors
New calibrations of CR39 and Makrofol nuclear track detectors have been
obtained using 158 A GeV Pb (82+) and In (49+) ions; a new method for the bulk
etch rate determination, using both cone height and base diameter measurements
was developed. The CR39 charge resolution based on the etch-pit base area
measurement is adequate to identify nuclear fragments in the interval 7 <=
Z/beta <= 49. For CR39 the detection threshold is at REL~50 MeV cm^2/g,
corresponding to a nuclear fragment with Z/beta~7. Base cone area distributions
for Makrofol foils exposed to Pb (82+) ions have shown for the first time all
peaks due to nuclear fragments with Z > 50; the distribution of the etched cone
heights shows well separated individual peaks for Z/beta = 78 - 83 (charge
pickup). The Makrofol detection threshold is at REL 2700 MeV cm^2/g,
corresponding to a nuclear fragment with Z/beta~50.Comment: 11 pages, 5 EPS figures. Submitted to Nucl. Instr. Meth.
Search for nuclearites with the SLIM detector
We discuss the properties of cosmic ray nuclearites, from the point of view
of their search with large nuclear track detector arrays exposed at different
altitudes, in particular with the SLIM experiment at the Chacaltaya high
altitude lab (5290 m a.s.l.). We present calculations concerning their
propagation in the Earth atmosphere and discuss their possible detection with
CR39 and Makrofol nuclear track detectors.Comment: 11 pages, 6 figure
Fragmentation of very high energy heavy ions
A stack of CR39 (C12H18O7)n nuclear track detectors with a Cu target was
exposed to a 158 A GeV lead ion beam at the CERN-SPS, in order to study the
fragmentation properties of lead nuclei.
Measurements of the total, break-up and pick-up charge-changing cross
sections of ultrarelativistic Pb ions on Cu and CR39 targets are presented and
discussed.Comment: 4 pages, 3 EPS figures included with epsf, uses article.sty Talk
presented by M. Giorgini at the Int. Conf. on Structure of the Nucleus at the
Dawn of the Century, Bologna (Italy), May 29-June 3, 200
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