Spectral capabilities

Figure 4.12 shows the energy response matrix obtained by using the method described in section 4.3. The matrix has 8 energy channels with energies between 10 MeV and 50 GeV.

Figure 4.12: The AGILE Response Matrix of energy reconstruction using the Multiple Scattering method. In the abscissa are the true energy channels while in ordinate are the reconstructed energy channels .

To test the spectral capabilities of the AGILE energy reconstruction method, we simulate an observation of a point source for $10^6$ sec at 30 degree off-axis with background induced by mid-latitude diffuse $\gamma$-ray emission. The source spectrum is described by a power law:

$$F=k\bigl(\frac{E[{\rm Mev}]}{100}\bigr)^{-\alpha}$$ (4.20)

with input photon index $\alpha=2$ and differential flux $k = 1.5 \times 10^{-9} {\rm ~ ph~ cm^{-2} ~ s^{-1}~ MeV^{-1}}$ at $E = 100 ~Mev$.
The reconstructed fit values obtained using the response matrix are (at 90% conf. lev.):

$$\alpha=1.99 \pm 0.2$$ (4.21)

and

$$k=1.56 \times 10^{-9} \pm 1.4 \times 10^{-10} {\rm ~ ph~ cm^{-2} ~ s^{-1}~ MeV^{-1}}$$ (4.22)

The preliminary results obtained for the spectral resolution are shown in figure 4.13.

Figure 4.13: Spectral deconvolution for the simulated observation of a point source for $10^6$ sec at 30 degree off-axis from Tracker-only information. preliminary plots [Giuliani et al., 2003b]