Fig. 1.
Schematic cross-section view of TPX2 chip bump-bonded to Si sensor with examples of neutron registration: through conversion in polyethylene (left) or by nuclear reaction with Si nucleus (right).
Fig. 2.
The photograph of the MiniPIX TPX2 detector with applied layers (left). The X-ray image of the layers applied on the sensor substrate (middle). Areas of the sensor covered by different converter layers in color (right).
Fig. 3.
Arrangement of experimental testing of the TPX2 detector by fast neutrons.
Table 1.
Selected interactions of fast neutrons in Si sensor and conversion layer with their Q values and total energy of recoils for interacting neutrons with kinetic energy of 3.55 MeV and 15.7 MeV with parameters for elastic scattering on hydrogen in the converter layer
| Interaction | Q value (MeV) | Total kinetic energy of charged recoils (MeV) | |
|---|---|---|---|
| @ 3.55 MeV neutrons | @ 15.7 MeV neutrons | ||
| 28Si(n,n′)28Si (elastic sc.) | 0 | up to 0.47 | up to 2.09 |
| 28Si(n,n′)28Si* | −1.779 | 1.771 | 13.921 |
| 28Si(n,α)25Mg | −2.654 | 0.896 | 13.046 |
| 28Si(n,α)25Mg* | −3.239 | 0.311 | 12.461 |
| 28Si(n,α)25Mg** | −3.628 | − | 12.072 |
| 28Si(n,α)25Mg*** | −4.266 | − | 11.434 |
| 28Si(n,α)25Mg**** | −4.618 | − | 11.082 |
| 28Si(n,α)25Mg***** | −5.455 | − | 10.245 |
| 28Si(n,α)25Mg****** | −6.059 | − | 9.641 |
| 28Si(n,p)28Al | −3.860 | − | 11.840 |
| 28Si(n,d)27Al | −9.360 | − | 6.340 |
| 28Si(n,γ)29Si | 8.474 | 12.024 | 24.174 |
| H(n,p)n | 0 | up to 3.55 | up to 15.7 |
Table 2.
Projected ranges of protons in converter layers applied on the sensor surface according to SRIM [21]
| Proton energy (MeV) | Kapton polyimide film C22H10N2O5 (1.42 g/cm3, 10 μm) | Polyethylene (C2H4)n (0.93 g/cm3, 50–150 μm) |
|---|---|---|
| Projected range (μm) | ||
| 3.55 | 152.24 | 190 |
| 15.70 | 2090 | 2700 |
Fig. 4.
Tracks of the first 2000 particles registered by the TPX2 detector with applied filtration are described in the left column for two energies of interacting neutrons: 3.55 MeV (middle column) and 15.7 MeV (right column).
Fig. 5.
The cross-sections of selected reactions on 28Si and elastic scattering on 1H, 12C, 14N, and 16O as a function of neutron kinetic energy obtained from ENDF/B-VII.1 [24].