P. Leleux

INTEGRAL/SPI ground calibration

Three calibration campaigns of the spectrometer SPI have been performed before launch in order to determine the instrument characteristics, such as the effective detection area, the spectral resolution and the angular resolution. Absolute determination of the effective area has been obtained from simulations and measurements. At 1 MeV, the effective area is 65 cm^2 for a point source on the optical axis, the spectral resolution ~2.3 keV. The angular resolution is better than 2.5 deg and the source separation capability about 1 deg. Some temperature dependant parameters will require permanent in-flight calibration.

SPI: A high resolution imaging spectrometer for INTEGRAL

SPI (Spectrometer for INTEGRAL) is a high spectral resolution gamma-ray telescope using cooled germanium detectors that will be flown on board the INTEGRAL mission in 2001. It consists of an array of 19 closely-packed germanium detectors surrounded by an active bismuth germanate (BGO) anti-coincidence shield. The instrument operates over the energy range 20 keV to 8 MeV with an energy resolution of 1–5 keV. A tungsten coded-aperture mask located 1.7 m from the detector array provides imaging over a 15° fully-coded field-of-view with an angular resolution of ∼3°. The point source narrow-line sensitivity is estimated to be 3–7×10−6 ph cm−2 s−1 over most of the range of the instrument (E>200 keV) for a 106 s observation. With its combination of high sensitivity, high spectral resolution and imaging, SPI will improve significantly over the performance of previous instruments such as HEAO-3, OSSE, and Comptel. It can be expected to take a major step forward in experimental studies in nuclear astrophysics. The ...

The SPI Spectrometer for the integral mission

SPI (Spectrometer for INTEGRAL) is a high spectral resolution gamma-ray telescope to be flown on board the ESA mission INTEGRAL. It consists of an array of 19 closely packed Germanium detectors surrounded by an active anticoincidence shield of EGO. The imaging capabilities of the instrument are obtained with a tungsten coded aperture mask located 1.7 m from the Ge array. The fully coded field-of-view is 16 degrees and the angular resolution approximate to 2 degrees. The energy range extends from 20 keV to 8 MeV with a typical energy resolution approximate to 2 keV at 1 MeV. The point-source narrow-line sensitivity is estimated to be (3-7) x 10(-6) ph/cm(-2) s(-1) over most of the energy range of the instrument (E > 200 keV) for a 10(6) s observing time. With these expected performances a major step forward can be expected in fine gamma-ray spectroscopy of astrophysical objects.

Neutron-proton capture total cross section between 38 and 73 MeV

Summary form only given, substantially as follows. The authors have measured the n-p capture total cross section at 38, 43, 48, 53, 58, 63 and 73 MeV; this energy range overlaps the questioned region of the deuteron photodisintegration. Neutrons are produced by the /sup 7/Li(p,n) reaction at 0 degrees . Deuterons from capture processes are emitted in a narrow forward cone (less than +/-7 degrees ); the time of flight between two NE102 scintillators, as well as Delta E and E signals from those scintillators, are used to select deuterons. Protons from n-p elastic scattering at 3 degrees lab are also detected. The capture total cross section is thus normalized to the well-known n-p differential cross section at backward c.m. angles.