No abstract

Radiocarbon analysis in annual rings of a teak tree (Tectona grandis) is reported in comparison with previously published results. Samples (disks) were collected from Hoshangabad (22°30′N, 78°E), Madhya Pradesh, in central India. The previously published sample was collected from Thane (19°12′N, 73°E), Maharashtra, near the west coast of India (Chakraborty et al. 1994). Two short Δ14C time series were reconstructed with these tree samples to capture the bomb peak of atmospheric 14C and the spatial variability in this record. These time series represent the periods 1954–1977 and 1959–1980 for Hoshangabad and Thane, respectively. The 14C peaks in these places appear around 1964–1965. The Hoshangabad tree records a peak Δ14C value of 708 ± 8%, which conforms to the peak value of Northern Hemisphere Zone 3 as described in Hua and Barbetti (2004). But the peak Δ14C at Thane is somewhat less (630 ± 8%) probably due to the dilution by fossil fuel CO2 free of 14C emanating from the neighboring industrial areas. This depletion of peak values has been used to estimate the local emission of fossil fuel CO2, which is approximately 2.3% of the background atmospheric CO2 concentration.

Ion Beam Induced Luminescence (IBIL) combined with Ion Beam Induced ChargeCollection (IBICC) is applied in a quantitative study of the IBIL generation yield and detection efficiency for several plastic phosphor materials. The main purpose of this study is to search for strongly luminescent materials that can be used to easily coat samples to be studied with Ion Photon Emission Microscopy (IPEM). A special focus is given to plastic scintillation materials because thin films are easily prepared, and such films have already been used for single event triggering. The emission yield was found to be low for typical Bicron pIastic phosphors (onIy -70 photons/ion/micron).The totaI collection, transmission and photon detection efficiency of the optical microscope used in this study was determined to be only -0.00003. For thin film plastic phosphors -20 microns thick, the detection efficiency was only 0.04 photons/ion. This means that using these plastics, IPEM would need to be performed with -~o~more beam fluence to obtain data, such as IBICC, similar to a standard scanned nuclear microprobe. Improvements are discussed.. ., DISCLAIMER

To design more radiation-tolerant Integrated Circuits (ICS), it is necessary to design and test accurate models of ionizing radiation induced charge collection dynamics with microcircuits.A new technique, Diffusion Time Resolved Ion Beam Induced Charge Collection (DTNBICC), is used to measure the average arrival time of the diffused charge, which can be related to the first moment (or the average time) of the arrival carrier density at the junction. Specially designed stripe-like test junctions are experimentally studied using a 12 MeV carbon microbeam with a spot size of-1 pm. The relative arrival time of ion-generated charge and the collected charge are measured using a multiple parameter data acquisition system. A 2-D device simulation code, MEDIC1, is used to calculate the charge collection dynamics on the stripe-like test junctions. The simulations compare very \vell with experimental microbeam measurements.The results show the importance of the diffused charge collection by junctions, which is 1

Various devices can be realized on strained GeSi/Si substrates by doping the substrate with different impurities such as As. As is an n-type dopant in both Ge and Si. As cross contamination can also arise during germanium preamorphization implantation due to inadequate mass resolution in the implanter. Thus, it is important to be able to accurately measure low-level As concentrations in the presence of Ge. Secondary ion mass spectrometry (SIMS) is the standard technique for these types of measurements but is constrained by mass interferences from molecular ions (74GeH, 29Si30Si16O). The trace element accelerator mass accelerator technique allows the breakup of interfering molecules. As is measured in a GeSi matrix with sensitivity significantly better than SIMS.