Measurement of the Cosmic Ray Helium Energy Spectrum from 70 GeV to 80 TeV with the DAMPE Space Mission.

The measurement of the energy spectrum of cosmic ray helium nuclei from 70 GeV to 80 TeV using 4.5 years of data recorded by the Dark Matter Particle Explorer (DAMPE) is reported in this work. A hardening of the spectrum is observed at an energy of about 1.3 TeV, similar to previous observations. In addition, a spectral softening at about 34 TeV is revealed for the first time with large statistics and well controlled systematic uncertainties, with an overall significance of 4.3σ. The DAMPE spectral measurements of both cosmic protons and helium nuclei suggest a particle charge dependent softening energy, although with current uncertainties a dependence on the number of nucleons cannot be ruled out.

Feasibility study on the use of CMOS sensors as detectors in radioguided surgery with ß-- emitters.

Radioguided surgery (RGS) is a medical practice which thanks to a radiopharmaceutical tracer and a probe allows the surgeon to identify tumor residuals up to a millimetric resolution in real-time. The employment of ß- emitters, instead of γ or ß+, reduces background from healthy tissues, administered activity to the patient, and medical exposure. In a previous work the possibility of using a CMOS Imager (Aptina MT9V011), initially designed for visible light imaging, to detect ß- from 90Y or 90Sr sources has been established. Because of its possible application as counting probe in RGS, the performances of MT9V011 in clinical-like conditions were studied.1 Through horizontal scans on a collimated 90Sr source of different sizes (1, 3, 5, 7 mm), we have determined relationships between scan fit parameters and the source dimension, namely A quadratic correlation and a linear dependency of, respectively, signal integrated over scan interval, and maximum signal against source diameter, are determined. Horizontal scan measurements on a source, interposing collimators of different size, aim to determine relationships or correlations between scan fit parameters and source dimension. A quadratic correlation and a linear dependency of, respectively, signal integrated over scan interval, and maximum signal against source diameter are determined. In order to get closer to clinical conditions, agar-agar phantoms containing 90Y with different dimensions and activities were prepared. A 90Y phantom is characterized by a central spot and a ring all around, for simulating both signal (tumor) and background (surrounding healthy tissue). The relationship found between scan maximum and 90Sr source diameter is then exploited to extract the concentration ratio between spot and external ring of the 90Y phantom. This observable, defined as the ratio between the tumor and the nearby healthy tissues uptake simulates the Tumor-to-Non-tumor Ratio (TNR). With the aim of evaluating the sensor's ability to discriminate signal from background relying on the significance parameter, a further 90Y phantom, featuring a well-known and clinical-like activity will mimic the signal only condition. This result is used to extrapolate to different source sizes, after having estimated the background for various TNR. The obtained significance values suggest that the MT9V011 sensor is capable of distinguishing a signal from an estimated background, depending on the interplay among TNR, acquisition time and tumor diameter.

Measurement of the cosmic ray proton spectrum from 40 GeV to 100 TeV with the DAMPE satellite.

The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2 1/2 years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.

Cervical ultrasound assessment of thyroid nodules at risk of malignancy: single-center experience.

AIM: The increasing diagnosis of thyroid nodules makes proper assessment of their nature and course of treatment essential, considering that thyroidectomy may be unnecessary and only contribute to higher healthcare system costs. Although criteria have been proposed for the stratification of these patients according to risk by use of cervical ultrasound and fine needle aspiration biopsy (FNAB), not all medical units may be equipped or have access to trained medical professionals to perform FNAB. The aim of this study was to show that cervical ultrasound may be sufficient for the evaluation of thyroid nodules in the treatment decision-making process. PATIENTS AND METHODS: 206 patients with single thyroid nodules and nodular goiter were assessed through cervical ultrasound and FNAB for the correlation between pretreatment classification and final diagnosis on histological examination. RESULTS: 26.5% of single nodes proved malignant on paraffin studies, as compared to only 14% of nodular goiters. FNAB recorded a sensibility of 33.3%, specificity of 93.3%, false-negative rate of 50% and false-positive rate of 12.5%, whereas cervical ultrasound recorded a sensibility of 92.3%, specificity of 75.3%, false-negative rate of 2.8% and false-positive rate of 48.9%. CONCLUSION: Cervical ultrasound evaluation is a reliable method in the preoperative diagnosis of thyroid cancer patients.

Absorbed dose rate estimation for protons, leptons and helium observed with AMS01 experiment in low earth orbit during STS-91 mission.

The Alpha Magnetic Spectrometer (AMS01), a high-sensitivity particle spectrometer, was successfully flown for 10 d in June 1998 (STS91) in the orbit of the International Space Station (51.7 degrees, -380 km). A high-statistics dataset of galactic cosmic rays were measured as a function of geomagnetic latitude, including the primary protons, leptons and helium as well as the trapped and quasi-trapped proton and lepton components. In this paper, the absorbed dose rate owing to the protons, leptons and helium are presented and compared with measurements made by other instruments flown on the same mission.

[Value of ultrasound in preoperative exploration of parotid tumors]. / La valeur de l'échographie dans l'exploration pré-opératoire des tumeurs parotidiennes.

Ultrasound image were compared with operative findings and gross pathology and histology appearances in 28 patients with parotid gland tumors (24 benign and 4 malignant). Ultrasound exploration provides precise data on localization, shape, size, outline, homogenicity of tumor contents and position of lesion in relation to pharyngeal wall. Clearly defined ultrasound images were detected in all benign but few malignant tumors, which presented mainly diffuse images. Non-homogeneous density of images, showing presence of intratumoral necrotic zones, was identified in all cases of malignant tumors but very few cases of benign lesions. Ultrasound imaging defines probable nature of a parotid tumor, probability enhanced by combining other exploratory investigations, but provides precise data on physical nature of tumor, of value during surgery.