SIXS-P Detector Response to Electrons
and Protons
Esa Kallio
for the SIXS team
SIXS
nadir
Al
collimator
body
Cage structure
enclosing the
detectors
Al+W
collimator
rings
SIXS-P operation principle
Incident
particles
Particles penetrating the foils deposit energy
in one Side Detector and possibly the Core Detector.
Two signals used to identify species and determine energy.
Core detector
Pulse-height analysis
(Geant4 simulation, flat spectra)
No pulse from Core
Pulse from Side & Core
e
p
p
Side
e
Core
Side
Be
Be
Kapton
Kapton
Side
Side
Core
Both pulses are digitized with 6-bit
logarithmic resolution
Core
SIXS-P Data products
Energy spectra of electrons and protons in five viewing directions
and 8-second time resolution
• Proton energy channels
–
–
–
–
–
–
–
–
–
P1: 1.05 – 1.15 MeV
P2: 1.15 – 1.35 MeV
P3: 1.35 – 1.9 MeV
P4: 1.9 – 3.2 MeV
P5: 3.2 – 6.1 MeV
P6: 6.1 – 10 MeV
P7: 10 – 17 MeV
P8: 17 – 30 MeV
P9: > 30 MeV
P1 and P2 respond also to electrons at
energies 330 – 500 keV and 500 – 700 keV.
• Electron energy channels
–
–
–
–
–
–
–
E1: ~50 – 70 keV
E2: 70 – 100 keV
E3: 100 – 180 keV
E4: 180 – 330 keV
E5: ~300 – 1000 keV
E6: 1000 – 3000 keV
E7: > 3000 keV
Proton response in “Side Only” channels
1.35 MeV
e
p
1
Si
CsI(Tl)
Protons at E > 1.35 MeV already cleanly
separated from electrons
Kapton
Foils stop E < 0.9 MeV protons
Incident proton energy (MeV)
Be
Measured energy (MeV)
Energy response (Side detectors)
Protons (Eresidual = Side)
a = 3.553 keV/ch
b = –476 keV
Electrons (Eresidual = Side)
a = 4.213 keV/ch
b = –735 keV
Side detector energy response is linear but different parameters have to be used for
protons (high pulses) and electrons (low pulses). All five detectors have individual response.
Energy response (Core)
Protons
a’ = 127.2 ch
b’ = 56.6 ch MeV–c’
c’ = 0.960
Electrons
a’ = 178.9 ch
b’ = 15.6 ch MeV–c’
c’ = 2.594
Core detector energy response is non-linear and different parameters have to be used
for protons (high pulses) and electrons (low pulses)
Combining the electron and proton
calibration curves for Core
An interpolating function can be used for both protons and electrons.
Conclusions
• Energy response of SIXS-P Detectors for electrons and
protons has been simulated and calibrated
• Side detectors (150-µm thick Si diodes) are linear over large
range of energies. However, different linear response for
protons (large pulses) and electrons (low pulses) is
observed.
• Core detector (CsI(Tl) scintillator with photodiode readout)
has a non-linear energy response, which is very different
for protons (high pulses) and electrons (low pulses). A
single non-linear fit function between energy and pulse
height can, however, be found.
• According to simulations and calibrations, SIXS-P will be
able to deliver the foreseen data products.