Study of nuclear reactions with intense, high-purity, low-energy radioactive ion beams using a versatile multi-configuration dual superconducting-solenoid system
Abstract A new device (TwinSol) installed at the Nuclear Structure Laboratory at the University of Notre Dame implements a pair of large-bore 6 T superconducting solenoids for producing relatively pure, high-intensity beams of exotic light nuclei at low-energies (10–80 MeV). Typical beams include 8 Li and 6 He (T 1/2
Resolving nuclear reaction products at solenoid focal spot
For studies of astrophysical interest and nuclear reactions with radioactive nuclei, charged particle products emitted from nuclear reactions such as 7Li + 9Be are routinely produced, separated and focused onto a focal spot by ion focusing separators such as a superconducting solenoid. The separation and focusing of desired ion groups onto the focal plane is however not complete, being also accompanied by unwanted ion groups. The mass- and energy-resolving but also the spatial focusing power of these separators are also limited and often spread out. In order to evaluate and determine and minimize these effects we decided to analyze the spectral and spatial distributions of ion reaction products at a superconducting solenoid. For this purpose we use the position-sensitive quantum-counting pixel detector Timepix which provides energy or time sensitivity per pixel. This device resolves different ion groups and measures the spectral and spatial spread distributions. Single ions are detected and individual ion groups can be identified and distinguished by multi-parameter event-by-event and pattern recognition analysis of the characteristic ion signal response in the pixelated detector. We present the capabilities of the technique on the indicated reaction above which is studied at the radioactive ion beam facility RIBRAS in Brazil. Several ion groups arriving at the focal plane are established such as 7,8Li, 4,6He and 3H together with their spatial and spectral distributions. The energy- and spatial-spread of the solenoid resolving power at the focal plane can be thus evaluated with a resolution of tens of keV and few µm, respectively. The detector serves moreover as an online verification and calibration imager for the ion optics separator and beam focusing monitoring. Results are presented for measurements with a 24 MeV 7Li beam and a thin 9Be target with the solenoid tuned for selection and focusing of produced radioactive 8Li.
Turbine blade temperature calculation and life estimation - a sensitivity analysis
Abstract The overall operating cost of the modern gas turbines is greatly influenced by the durability of hot section components operating at high temperatures. In turbine operating conditions, some defects may occur which can decrease hot section life. In the present paper, methods used for calculating blade temperature and life are demonstrated and validated. Using these methods, a set of sensitivity analyses on the parameters affecting temperature and life of a high pressure, high temperature turbine first stage blade is carried out. Investigated uncertainties are: (1) blade coating thickness, (2) coolant inlet pressure and temperature (as a result of secondary air system), and (3) gas turbine load variation. Results show that increasing thermal barrier coating thickness by 3 times, leads to rise in the blade life by 9 times. In addition, considering inlet cooling temperature and pressure, deviation in temperature has greater effect on blade life. One of the interesting points that can be realized from the results is that 300 hours operation at 70% load can be equal to one hour operation at base load.