1. Stanislav Pospíšil et al, Brightness Vidyo meeting
Fast neutron ToF measurement with TIMEPIX LANSCE neutron sources and nuclear science flight paths (combined ToA and ToT modes)
The layout of the LANSCE neutron sources and Nuclear Science flight paths
Time structure of the proton beam for typical Target-4 operation
Stanislav Pospíšil et al, Brightness Vidyo meeting

2. Fluences of different cluster types over energy
Curly tracks, dots and small blobs dominate nearly over the whole energy range
Asymmetric errorbars in x-direction due to binning of the measurement
Three humps are present at lower fast neutron energies (<1 MeV) -> dots
Stanislav Pospíšil et al, Brightness Vidyo meeting

3. Fluences below different conversion layers
In the lower energy region responses below LiF, PE, PE+Al seem to be a good indicator for neutron energies
- Threshold for PE+Al at ~ 3.4 MeV
- Enhanced signal below LiF up to 4 MeV
- Recoiled protons visible above 1.2 MeV
1.2 MeV
3.4 MeV
5 MeV
Stanislav Pospíšil et al, Brightness Vidyo meeting

4. Response of Timepix: Energy region 0.4 – 1.2 MeV
Mainly dots, curly tracks are found in this energy region
Heavy blobs below LiF indicate presence of slow/thermal neutrons
Also PE region shows slightly enhanced count rate
All types of clusters in this energy region integral picture (1000 events were considered)
Heavy tracks and heavy blobs in this energy region (139 events were found)
Stanislav Pospíšil et al, Brightness Vidyo meeting

5. Response of Timepix: Energy region 1.2 – 3.4 MeV
Heavy blobs below LiF indicate presence of slow/thermal neutrons
Clear signal of High Energy Transfer Particles (HETP) below PE
uncovered area shows also a few events
All types of clusters in this energy region integral picture (1000 events were considered)
Heavy tracks and heavy blobs in this energy region (full statistics events were found)
Stanislav Pospíšil et al, Brightness Vidyo meeting

6. Response of Timepix: Energy region 3.4 – 5.0 MeV
Clear signal of HETP below PE
Also in PE+Al region HETP are becoming visible
All types of clusters in this energy region integral picture (1000 events were considered)
Heavy tracks and heavy blobs in this energy region (full statistics – events were found)
Stanislav Pospíšil et al, Brightness Vidyo meeting

7. Response of Timepix: Energy region 5.0 – 10 MeV
Higher HETP count rate below PE and PE+Al
HETP: cluster still look roundly shaped
Almost no enhancement below LiF
All types of clusters in this energy region integral picture (1000 events were considered)
Heavy tracks and heavy blobs in this energy region (full statistics events were found)
Stanislav Pospíšil et al, Brightness Vidyo meeting

8. Response of Timepix: Energy region 10 – 30 MeV
Higher HETP count rate below PE and PE+Al (contrast to other regions begins to decrease)
HETP equally distributed below all other regions
HETP: Clusters become bigger and asymmetric
All types of clusters in this energy region integral picture (1000 events were considered)
Heavy tracks and heavy blobs in this energy region (full statistics events were found)
Stanislav Pospíšil et al, Brightness Vidyo meeting

9. Response of Timepix: Energy region 30 – 100 MeV
Still enhanced response below PE and PE+Al
Contrast to all other region is decreasing
Cluster are getting bigger and more and more asymmetric
All types of clusters in this energy region integral picture (1000 events were considered)
Heavy tracks and heavy blobs in this energy region (full statistics events were found)
Stanislav Pospíšil et al, Brightness Vidyo meeting

10. Response of Timepix: Energy region 100 – 300 MeV
HETP nearly equally distributed below all regions
HETP Cluster shapes
Are getting bigger and more and more asymmetric
Round clusters with outgoing tracks are seen
All types of clusters in this energy region integral picture (1000 events were considered)
Heavy tracks and heavy blobs in this energy region (full statistics events were found)
Stanislav Pospíšil et al, Brightness Vidyo meeting

11. Response of Timepix: Energy region 300 MeV +
HETP nearly equally distributed below all regions
All types of clusters in this energy region integral picture (1000 events were considered)
Heavy tracks and heavy blobs in this energy region (full statistics events were found)
Stanislav Pospíšil et al, Brightness Vidyo meeting

12. Stanislav Pospíšil et al, Brightness Vidyo meeting
Examples of heavy ionizing events induced by neutrons of different energies selected according their cluster sizes
Different colors and black numbers assigned to individual clusters indicate the energy of incoming neutrons as measured by means of the TOF technique
Stanislav Pospíšil et al, Brightness Vidyo meeting

13. Cluster shapes Timepix detector responses as a function of neutron kinetic energy
The ToF technique*) was used to assign the detector responses to the corresponding neutron energies (track by track).
Heavy events due to nuclear interactions appear
Peaks of resonance neutron elastic scattering
For me: Check, if there is a correlation between the appearance of curly tracks and the inelastic scattering to the first excited level of silicon – Ethreshold = 1.85 MeV –compton electrons!!!
+ compare measured peaks with the cross section for it
Number of different cluster types as a function of kinetic neutron energy!
Gammas from the 1st excited level of silicon (1.78 MeV)
*) see: B Bergmann et al 2014 JINST 9 C05048
Stanislav Pospíšil et al, Brightness Vidyo meeting

14. Stanislav Pospíšil et al, Brightness Vidyo meeting
TIMEPIX3
Thickness: 300µm
Bias: 90 V
Triggered
Data driven mode
T0 synch when trigger signal was received
Stanislav Pospíšil et al, Brightness Vidyo meeting

15. TIMEPIX3: Cluster shapes (detector responses) as a function of neutron kinetic energies
Peaks from neutron elastic scattering Si(n,n‘)Si
Stanislav Pospíšil et al, Brightness Vidyo meeting

16. TIMEPIX3: Examples of energy spectra for selected neutron energy intervals
Si(n,n)Si
Si(n,X)-reactions
Natural radioactivity and activation
Mixture of all possible effects (products leave the sensor)
Si(n,X)-reactions
Kremenek, Kroha – excitation function
Stanislav Pospíšil et al, Brightness Vidyo meeting

17. Edges identification by spectrum analysis and interpretation
Fit Fermi-function with background: 𝑓 𝐸 = 𝐴 𝑒 (𝐸− 𝐸 𝑒𝑑𝑔𝑒 ) +1 +𝐵+𝐶∙𝐸
Energy transfer to the silicon nucleus:
𝑇 𝑆𝑖,𝑚𝑎𝑥 = 4 𝑀 𝑆𝑖 𝑚 𝑛 𝑀 𝑆𝑖 + 𝑚 𝑛 𝑇 𝑛 =0.133∙ 𝑇 𝑛
→ Energy goes partly into displacement 𝐸 𝑁𝐼𝐸𝐿 (NIEL) and ionization 𝐸 𝑖𝑜𝑛.
Energy measured: 𝐸 𝑒𝑑𝑔𝑒 = 𝐸 𝑖𝑜𝑛.
→ Fraction of ionizing energy losses: 𝑓 𝑚𝑒𝑎𝑠, 𝑖𝑜𝑛 = 𝐸 𝑒𝑑𝑔𝑒 𝑇 𝑆𝑖,max = 𝐸 𝑒𝑑𝑔𝑒 ∙ 𝑇 𝑛
Stanislav Pospíšil et al, Brightness Vidyo meeting