Entanglement-secured single-qubit quantum secret-sharing

In single-qubit quantum secret sharing, a secret is shared between N parties via manipulation and measurement of one qubit at a time. Each qubit is sent to all N parties in sequence; the secret is encoded in the first participant's preparation of the qubit state and the subsequent participants' choices of state rotation or measurement basis. We present a protocol for single-qubit quantum secret sharing using polarization entanglement of photon pairs produced in type-I spontaneous parametric downconversion. We investigate the protocol's security against eavesdropping attack under common experimental conditions: a lossy channel for photon transmission, and imperfect preparation of the initial qubit state. A protocol which exploits entanglement between photons, rather than simply polarization correlation, is more robustly secure. We implement the entanglement-based secret-sharing protocol with 87% secret-sharing fidelity, limited by the purity of the entangled state produced by our present apparatus. We demonstrate a photon-number splitting eavesdropping attack, which achieves no success against the entanglement-based protocol while showing the predicted rate of success against a correlation-based protocol.Comment: 10 pages, 8 figure

Rapidly Growing Pancreatic Adenocarcinoma Presenting as an Irreducible Umbilical Hernia

Hernia sacs are a common anatomic pathology specimen, which rarely contain malignancy. We present a case of rapidly growing pancreatic adenocarcinoma, which initially presented as metastasis to an umbilical hernia sac. The patient was a 55-year-old male with a two-year history of umbilical hernia. Two months prior to herniorrhaphy, the hernia became painful and the patient experienced nausea and weight loss. The gross examination did not reveal distinct lesions. Microscopically, the hernia sac was diffusely infiltrated by moderately differentiated adenocarcinoma, which was positive for CK7 and pancytokeratin and negative for TTF-1, CK20, PSA, and CDX2. Clinical laboratory tests found elevated levels of CA 19-9 and CEA. Computed tomography scan with intravenous contrast showed a 5 cm ill-defined and hypoattenuating mass involving the pancreatic tail and body, as well as numerous ill-defined lesions in the liver and peritoneal carcinomatosis. The patient had an earlier noncontrast computed tomography scan four months prior to the surgery, which did not detect any lesions in the abdomen. This case highlights the importance of intravenous contrast with computed tomography for the evaluation of pancreatic lesions and also emphasizes the importance of thorough histologic evaluation of hernia sacs for the detection of occult malignancy

Beta particle measurement and dosimetry Requirements at NRC-licensed facilities

Researchers from Pacific Northwest Laboratroy (PNL) have conducted beta radiation measurements under laboratory and field conditions to assess the degree of the measurement problem and offer suggestions for possible remedies. The primary measurement systems selected for use in this study were the silicon (Si) surface barrier spectrometer system and the multielement beta dosimeter. Three boiling water reactors (BWRs), two pressurized water reactors (PWRs), and one fuel fabrication facility were visited during the course of the study. Although beta fields from cobalt-60 were the most common type found at commercial reactor facilities, higher energy beta fields were found at locations associated with spent fuel handling, liquid radioactive waste, and BWR turbine components. Commercially-available dosimeters and survey instruments were used to measure the same laboratory and licensee facility beta fields characterized with PNL's active and passive spectrometers. A prototype spectrometer was also used in the laboratory measurements. The commercial instruments and dosimeters used in this study typically responded low to the beta fields measured, especially where maximum beta energies were less than approximately 500 keV

Personnel neutron dose assessment upgrade: Volume 2, Field neutron spectrometer for health physics applications

Both the (ICRP) and the (NCPR) have recommended an increase in neutron quality factors and the adoption of effective dose equivalent methods. The series of reports entitled Personnel Neutron Dose Assessment Upgrade (PNL-6620) addresses these changes. Volume 1 in this series of reports (Personnel Neutron Dosimetry Assessment) provided guidance on the characteristics, use, and calibration of personnel neutron dosimeters in order to meet the new recommendations. This report, Volume 2: Field Neutron Spectrometer for Health Physics Applications describes the development of a portable field spectrometer which can be set up for use in a few minutes by a single person. The field spectrometer described herein represents a significant advance in improving the accuracy of neutron dose assessment. It permits an immediate analysis of the energy spectral distribution associated with the radiation from which neutron quality factor can be determined. It is now possible to depart from the use of maximum Q by determining and realistically applying a lower Q based on spectral data. The field spectrometer is made up of two modules: a detector module with built-in electronics and an analysis module with a IBM PC/reg sign/-compatible computer to control the data acquisition and analysis of data in the field. The unit is simple enough to allow the operator to perform spectral measurements with minimal training. The instrument is intended for use in steady-state radiation fields with neutrons energies covering the fission spectrum range. The prototype field spectrometer has been field tested in plutonium processing facilities, and has been proven to operate satisfactorily. The prototype field spectrometer uses a /sup 3/He proportional counter to measure the neutron energy spectrum between 50 keV and 5 MeV and a tissue equivalent proportional counter (TEPC) to measure absorbed neutron dose