A New Uniform Calibration Method for Double-Sided Silicon Strip Detectors
We proposed and implemented a new uniform calibration approach for double-sided silicon strip detector, named the self-calibration method (SCM). This method uses the strips on one side of the detector as references, to calibrate the strips on the other side, and vice versa. This calibration method has the inherent advantages that it can be run during the experiment corresponding exactly to the required particle type and energy range, and provides good statistics based on flexible selection of the event samples. Two strategies based on the same working principle but with deferent complexities, named simple SCM and overall SCM, were introduced and examined experimentally. The simple SCM requires less computation but a large number of events, while the overall SCM exhibits excellent performance even with a relatively small number of events.
Search for 7H in 2H+8He collisions
An experimental search for the low-lying 7 H resonance was performed with the 2 H( 8 He, 3 He) 7 H reaction studied at forward center-of-mass angles (6°-14°) with a 42 A MeV 8 He beam. No well-pronounced peak of 7 H was observed; however, the obtained spectrum was found to have a peculiarity at ~2 MeV above the t + 4n threshold. The data allow us to set a c.m.s. cross section level of ~30 μb/sr for the low-energy part of the 7 H spectrum. The test reaction 2 He 2 Be, 3 He) 11 Li, involving the same one-proton (d, 3 He) transfer, was studied simultaneously on a 71 A MeV satellite beam where a cross section of ≃1 mb/sr was measured for the population of the 11 Li ground state.
Two new organic reference materials for delta13C and delta15N measurements and a new value for the delta13C of NBS 22 oil.
Analytical grade L-glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L-glutamic acid reference materials with substantially different 13C and 15N abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L-glutamic acid and has a delta13C value of -26.24 per thousand relative to VPDB and a delta15N value of -4.52 per thousand relative to N2 in air. USGS41 was prepared by dissolving analytical grade L-glutamic acid with L-glutamic acid enriched in 13C and 15N. USGS41 has a delta13C value of +37.76 per thousand and a delta15N value of +47.57 per thousand. The delta13C and delta15N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (delta13C=+1.95 per thousand ), L-SVEC lithium carbonate (delta13C=-46.48 per thousand ), IAEA-N-1 ammonium sulfate (delta15N=0.43 per thousand ), and USGS32 potassium nitrate (delta15N=180 per thousand ) by on-line combustion continuous-flow and off-line dual-inlet isotope-ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of delta13C is better than 0.13 per thousand, and that of delta15N is better than 0.13 per thousand in 100-microg amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass-dependent fractionations, and isotope-ratio-scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a delta13C value for NBS 22 oil of -29.91 per thousand, in contrast to the commonly accepted value of -29.78 per thousand for which off-line blank corrections probably have not been quantified satisfactorily.