Abstract-Cosmic-ray exposure (CRE) ages and Mars ejection times were calculated from the radionuclide 81% with previously obtained CRE ages from the stable noble gas nuclei 3He, 21Ne, and 38Ar shows excellent agreement. This indicates that the method for the production rate calculation for the stable nuclei is reliable. In all martian meteorites we observe effects induced by secondary cosmic-ray produced epithennal neutrons. Epithermal neutron fluxes, @, (30-300 eV), are calculated based on the reaction 79Br(n, yp)gOKr. We show that the neutron capture effects were induced in free space during Mars-Earth transfer of the meteoroids and that they are not due to a pre-exposure on Mars before ejection of the meteoritic material. Neutron fluxes and slowing down densities experienced by the meteoroids are calculated and pre-atmospheric sizes are estimated. We obtain minimum radii in the range of 22-25 cm and minimum masses of 150-220 kg. These results are in good agreement with the mean sizes reported for model calculations using current semiempirical data.-

Abstract-Several solar gas rich lunar soils and breccias have trapped 40Ar/36Ar ratios >lo, although solar Ar is expected to yield a ratio of <0.01. Radiogenic 40Ar produced in the lunar crust from 40K decay was outgassed into the lunar atmosphere, ionized, accelerated in the electromagnetic field of the solar wind, and reimplanted into lunar surface material. The 40Ar loss rate depends on the decreasing abundance of 40K. In order to calibrate the time dependence of the 40Ar/36Ar ratio in lunar surface material, the period of reimplantation of lunar atmospheric ions and of solar wind Ar was determined using the 235U-136Xe dating method that relies on secondary cosmic-ray neutron-induced fission of 235U. We identified the trapped, fissiogenic, and cosmogenic noble gases in lunar breccia 14307 and lunar soils 70001-8, 70181, 74261, and 75081. Uranium and Th concentrations were determined in the 74261 soil for which we obtain the 235U-136Xe time of implantation of 3.252::; Ga ago. On the basis of several cosmogenic noble gas signatures we calculate the duration of this near surface exposure of 393 k 45 Ma and an average shielding depth below the lunar surface of 73 k 7 g/cm*.A second, recent exposure to solar and cosmic-ray particles occurred after this soil was excavated from Shorty crater 17.2 2 1.4 Ma ago. Using a compilation of all lunar data with reliable trapped Ar isotopic ratios and pre-exposure times we infer a calibration curve of implantation times, based on the trapped 40ArP6Ar ratio. A possible trend for the increase with time of the solar 3He/4He and 20NeP2Ne ratios of about 12%/Ga and about 2%/Ga, respectively, is also discussed.

DTRT plans for different treatment sites were generated and compared with VMAT plans. The delivery is suitable and dose comparisons demonstrate a high potential of DTRT to reduce dose to OARs using less dynamic trajectories than arcs, while target coverage is preserved.

Abstract-We report the elemental and isotopic composition of the noble gases as well as the chemical abundances in pyroxene, maskelynite/mesostasis glass, and bulk material of Shergotty and of bulk samples from Chassigny and Yamato 793605. The 4oK-4oAr isochron for the Shergotty minerals yields a gas retention age of 196 Ma, which is, within errors, in agreement with previously determined Rb-Sr internal isochron ages. Argon that was trapped at this time has a 40Ar136Ar ratio of 1100. For Chassigny and Y-793605, we obtain trapped 40Ar/36Ar ratios of 1380 and 950, respectively. Using these results and literature data, we show that the three shergottites, Shergotty, Zagami, and QUE 94001; the lherzolites ALH 77005, LEW 88516, and Y-793605; as well as Chassigny and ALH 84001 contain a mixture of Martian mantle and atmospheric Ar; whereas, the trapped 40Ar/36Ar ratio of the nakhlites, Nakhla, Lafayette, and Governador Valadares cannot be determined with the present data. We show that Martian atmospheric trapped Ar in Martian meteorites is correlated with the shock pressure that they experienced. Hence, we conclude that the Martian atmospheric gases were introduced by shock into the meteoritic material. For the Shergotty minerals, we obtain 3He-, 21Ne-, and 38Ar-based cosmic-ray exposure ages of 3.0 Ma, and for the lherzolite Y-793605,4.0 Ma, which confirms our earlier conclusion that the lherzolites were ejected from Mars -1 Ma before the shergottites. Chassigny yields the previously known ejection age of 1 I .6 Ma.