Novel deuterium-tritium (DT) neutron activation diagnostics for increased neutron yield operations at Sandia's Z-facility (invited).

As inertial confinement fusion experiments at Sandia National Laboratories' Z-facility begin using deuterium-tritium (DT) fuels, the expected DT-neutron yields are expected to increase many orders of magnitude. This brings about the need for diagnostics that have a significantly higher dynamic range of operation and ability to obtain yields where there will be significant radiation holds. Using the current activation diagnostic infrastructure at the Z-facility, a pair of activation diagnostics are being developed. The first is fluorine activation, which will be used in a similar manner to current copper activation diagnostics that are fielded in a rabbit for quick removal from the experiments without opening the vacuum experiment containment. The second is a prompt DT-neutron detector that exploits the activation of oxygen with similar operation characteristics as the current Be-probes fielded at Z. We will discuss the design of this pair of instruments, along with calibration work performed at Sandia's Ion Beam Laboratory in support of the development and anticipated instrument performance.

Neutron source reconstruction using a generalized expectation-maximization algorithm on one-dimensional neutron images from the Z facility.

Magnetized Liner Inertial Fusion experiments have been performed at the Z facility at Sandia National Laboratories. These experiments use deuterium fuel, which produces 2.45 MeV neutrons on reaching thermonuclear conditions. To study the spatial structure of neutron production, the one-dimensional imager of neutrons diagnostic was fielded to record axial resolved neutron images. In this diagnostic, neutrons passing through a rolled edge aperture form an image on a CR-39-based solid state nuclear track detector. Here, we present a modified generalized expectation-maximization algorithm to reconstruct an axial neutron emission profile of the stagnated fusion plasma. We validate the approach by comparing the reconstructed neutron emission profile to an x-ray emission profile provided by a time-integrated pinhole camera.

Demonstration of improved laser preheat with a cryogenically cooled magnetized liner inertial fusion platform.

We report on progress implementing and testing cryogenically cooled platforms for Magnetized Liner Inertial Fusion (MagLIF) experiments. Two cryogenically cooled experimental platforms were developed: an integrated platform fielded on the Z pulsed power generator that combines magnetization, laser preheat, and pulsed-power-driven fuel compression and a laser-only platform in a separate chamber that enables measurements of the laser preheat energy using shadowgraphy measurements. The laser-only experiments suggest that ∼89% ± 10% of the incident energy is coupled to the fuel in cooled targets across the energy range tested, significantly higher than previous warm experiments that achieved at most 67% coupling and in line with simulation predictions. The laser preheat configuration was applied to a cryogenically cooled integrated experiment that used a novel cryostat configuration that cooled the MagLIF liner from both ends. The integrated experiment, z3576, coupled 2.32 ± 0.25 kJ preheat energy to the fuel, the highest to-date, demonstrated excellent temperature control and nominal current delivery, and produced one of the highest pressure stagnations as determined by a Bayesian analysis of the data.

Neutron time-of-flight detectors (nTOF) used at Sandia's Z-Machine.

Neutron time-of-flight (nTOF) detectors have been used on Sandia National Laboratories' Z-Machine for inertial confinement fusion and magnetized liner fusion experiments to infer physics parameters including the apparent fuel-ion temperature, neutron yield, the magnetic-radius product (BR), and the liner rho-r. Single-paddle, dual-paddle, and co-axial scintillation nTOF detectors are used in axial lines-of-sight (LOS) and LOS that are 12° from the midplane. Detector fabrication, characterization, and calibration are discussed.

Inferring neutron yields using indium activation samples for small fractions of tritium added to deuterium fuel in inertial confinement fusion (ICF) experiments.

In inertial confinement fusion experiments, the neutron yield is an important metric for thermonuclear fusion performance. Neutron activation diagnostics can be used to infer neutron yields. The material used for neutron activation diagnostic undergoes a threshold reaction so that only neutrons having energies above the threshold energy are observed. For thermonuclear experiments using deuterium (D) and tritium (T) fuel constituents, neutrons arising from D + D reactions (DD-neutrons) and neutrons resulting from D + T reactions (DT-neutrons) are of primary interest. Indium has two neutron activation reactions that can be used to infer yields of DD-neutrons and DT-neutrons. One threshold is high enough that only DT-neutrons can induce activation, the second reaction can be activated by both DD-neutrons and DT-neutrons. Thus, to obtain the DD-neutron yield, the contribution made by DT-neutrons to the total induced activity must be extracted. In DD-fuel experiments, DT-neutrons arise from secondary reactions, which are significantly lower in number than primary DD-neutrons, and their contribution to the inferred DD-neutron yield can be ignored. When the DD- and DT-neutron yields become comparable, such as when low tritium fractions are added to DD-fuel, the contribution of DT-neutrons must be extracted to obtain accurate yields. A general method is described for this correction to DD-neutron yields.

A neutron recoil-spectrometer for measuring yield and determining liner areal densities at the Z facility.

A proof-of-principle CR-39 based neutron-recoil-spectrometer was built and fielded on the Z facility. Data from this experiment match indium activation yields within a factor of 2 using simplified instrument response function models. The data also demonstrate the need for neutron shielding in order to infer liner areal densities. A new shielded design has been developed. The spectrometer is expected to achieve signal-to-background greater than 2 for the down-scattered neutron signal and greater than 30 for the primary signal.

Current concepts in breast reconstruction.

Breast cancer is the leading malignancy in women in the United States. Breast reconstruction is an important aspect in the treatment regime for breast cancer. Reconstruction now is a daily occurrence, providing women with a life-enhancing opportunity. Women contemplating reconstruction may choose from a broad menu of options allowing for tailored care.

Breast reconstruction with tissue expanders: obtaining an optimal result.

A large personal experience with breast reconstruction using tissue expanders (149 patients with Radovans, and more than 150 patients with Beckers), with many suboptimal results especially in the early learning stages, has brought about changes in approach offering a much higher probability of acceptable breasts. This report attempts to combine multiple factors useful in yielding such results. Areas addressed include immediate versus delayed reconstruction, selection of candidates, selection of expander type, appropriate placement of expander at a site minimizing the requirement for pocket modification, choosing the optimal size expander, importance of maximal overexpansion to yield a good submammary fold, and means of determining adequate overexpansion to match an unmodified contralateral breast and the risks inherent in overexpansion. Timing, interval, and length of maintenance of hyperexpansion are described along with deflation and timing of port removal. Both the skate and star techniques of nipple and areolar reconstruction in the hyperexpanded patient yield very acceptable results despite thinned skin and minimal subcutaneous tissue. Good, satisfactory, and suboptimal clinical results will be presented. In our experience, tissue expansion reconstruction offers distinct advantages in a large majority of patients with the proviso that patients are willing to accept the time required for hyperexpansion and the waiting period for deflation.

Hemifacial spasm and craniovertebral anomaly.

Two patients with congenital anomaly of the craniovertebral junction causing disabling hemifacial spasm (HFS) are presented. In one patient, complete cessation of the HFS occurred for a period of two years following simple bony decompression of the craniovertebral junction raising unanswered questions as to the exact pathogenesis of HFS. Eventually both patients required microvascular decompression at the root entry zone of the facial nerve.

Familial intracranial aneurysms: report of three families.

The problem of intracranial aneurysm causing subarachnoid hemorrhage in several members of three different families is illustrated and discussed in this report.

Familial intracranial gliomas.

The pedigree of two interrelated families with 10 affected members suffering from malignant supratentorial gliomas is reported. In addition, three other unrelated families with two members each who were treated for different types of brain tumors are described. Genetic implications are discussed.

Combined testing of anterior pituitary gland with insulin, thyrotropin-releasing hormone, and luteinizing hormone-releasing hormone.

Provocative tests of hypothalamic-pituitary function were performed in 20 healthy subjects to learn whether the simultaneous testing by three agents--insulin, thyrotropin-releasing hormone, and luteinizing hormone-releasing hormone--was feasible. The responses to simultaneous testing on one day did not differ significantly from those to testing on three separate days. The time and expense of pituitary-hypothalamic testing can thus be much reduced with no impairment of reliability and with no increased risk to the patient.

Adult diastematomyelia: a complex dysraphic state.

It is rare for patients with diastematomyelia to manifest initial symptoms in adult life. Clinical, radiological, and surgical features of a patient with symptomatic adult diastematomyelia are presented. Pathogenetic mechanisms are considered to include a variety of congenital spinal anomalies, distinct from the spur, as well as mechanical factors.

Acute spinal cord compression by subarachnoid and subdural hematoma occurring in association with brachial plexus avulsion. Case report.

The authors report a case of acute spinal cord compression caused by a subarachnoid and subdural hematoma. This occurred following traumatic brachial plexus avulsion. It is believed to be the first such case recorded.

Treatment of carotid cavernous fistula by intravascular occlusion using a balloon catheter.

The surgical treatment of carotid cavernous fistula gradually evolved into a "trapping" technique. This technique includes ligation of the cervical internal carotid artery, clipping of the intracranial portion distal to the fistula and often embolization of the isolated segment. The development of embolization techniques using intravascular balloon catheters greatly simplified this treatment. The authors report a case of spontaneous carotid cavernous fistula in which obliteration was achieved by an intracarotid balloon catheter. This was inserted by direct puncture of the carotid artery, which had been exposed by a simple neck incision. The patient's visual acuity was preserved. The efficacy, ease and safety of this method are emphasized.