Observed and modeled background in the HIREGS  IV unsegmented Ge detectors. The data are from the flight 94-95 and the calculations are for the continuum background. The beta decay components have been taken from Naya et al. (1996, N.I.M, A368, 832) and scaled with the ratio of the rates in the 198 keV line between HIREGS and HEXAGONE II.The photonic components have been estimated with Monte-Carlo simulations using the GEANT code and scaled to fit the continuum background at high energy (dominated by the shield leakage component).

Comparison of the calculated and the modeled continuum background of HIREGS IV. The differences between the model and the measurement is also presented.

Comparison of the calculated and the modeled continuum background of HIREGS IV between 0.2 MeV and 1.2 MeV (PSD energy range). The estimated b- localized component is also shown. The ratio between the calculation and the measurement is presented in the bottom part. Numerical values are listed in the table below

Estimations of the fraction of total continuum background rate induced by b- localized decays. Two cases have been considered: ratio between the calculated beta component and total modeled continuum background, and,  ratio between the calculated beta component and total measured continuum background. Numerical values are listed below (the rates are in counts s^-1 cm^-3 MeV^-1).

E (MeV)         b- loc           calculated      measured     %.         fb (b-/c)         fb (b- /m)
2.000e-01     4.007e-02     1.655e-01     2.730e-01     39.4     2.421e-01     1.468e-01
3.000e-01     4.266e-02     1.226e-01     1.730e-01     29.1     3.481e-01     2.466e-01
4.000e-01     4.259e-02     1.007e-01     1.250e-01     19.4     4.228e-01     3.407e-01
5.000e-01     4.008e-02     8.528e-02     1.000e-01     14.7     4.699e-01     4.008e-01
6.000e-01     3.625e-02     7.262e-02     7.730e-02     6.1       4.991e-01     4.689e-01
7.000e-01     3.160e-02     6.215e-02     6.770e-02     8.2       5.084e-01     4.667e-01
8.000e-01     2.613e-02     5.233e-02     5.460e-02     4.2       4.993e-01     4.785e-01
9.000e-01     1.968e-02     4.259e-02     4.920e-02     13.4     4.619e-01     3.999e-01
1.000e+00    1.333e-02     3.344e-02     4.100e-02     18.4     3.986e-01     3.251e-01
1.100e+00    9.438e-03     2.725e-02     3.590e-02     24.1     3.464e-01     2.629e-01
1.200e+00    6.762e-03     2.267e-02     3.340e-02     32.1     2.983e-01     2.025e-01