1. Tank Calibration
Pierre Auger Observatory
Gonzalo Rodriguez
Universidad de Santiago de Compostela
Astroparticle group
for the Pierre Auger Collaboration
1
Trasgo Project
2. Pierre Auger Observatory
research goals
• Energy Spectrum of UHECR (E > 1018 eV)
-> Shape of the spectrum in the region of the GZK feature
• Arrival Direction Distribution
-> Search for departure from isotropy - point sources
• Mass Composition: nuclei, photons, neutrinos,
etc.
2
3. Pierre Auger Observatory
research goals
• Energy Spectrum of UHECR (E > 1018 eV)
-> Shape of the spectrum in the region of the GZK feature
• Arrival Direction Distribution
-> Search for departure from isotropy - point sources
• Mass Composition: nuclei, photons, neutrinos,
etc.
•
And also...
Why we are here?
When we are going to disappear?
3
10. Event reconstruction: S(1000m)
Example Event (48°, E~70 EeV)
Reconstruction
procedure:
χ²-method to fit angles (θ,φ)
Likelihood method to fit
a NKG-type function
Fitting parameters
core
S(1000m)
S(1000m)
Slope β fixed
4
10
1000m
11. Fluorescence Reconstruction
Electromagnetic
energy
- Fluorescence energy almost
MC independent. SD tank
EFD = finv x Eem
11
16. VEM: Vertical Equivalent Muon
The Cherenkov light is measured in units of the signal
produced by a:
Vertical and Central Through-going Muon.
16
17. VEM: Vertical Equivalent Muon
The Cherenkov light is measured in units of the signal
produced by a:
Vertical and Central Through-going Muon.
We use:
Atmospheric muons
passing through the
detector at a rate of
2500Hz
1 minute ~ 150000 events
17
21. Charge histograms and their relation to a VEM
trigger threshold 0.2IpeakVEM
For the sum of the 3 PMTs
QpeakVEM = 1.09 VEM
Individual PMTs
QpeakVEM = 1.03 VEM 21
22. From simulations we can understand
the charge histrograms structure
Particles Flux Charge histograms
22
23. From simulations we can understand
the charge histrograms structure
Particles Flux Charge histograms
23
24. The calibration is done in 3 main steps:
- The high voltage of each PMT is adjust to have approximately the
same QpeakVEM in each PMT.
- Each PMT has a single rate spectrum. Then we adjust the trigger
thershold to have a single a rate of 100Hz at IpeakVEM = 150 ch.
- This choice sets up each of the PMT to have approximately 50ch /
IpeakVEM.
- Continually perform a local calibration to determine the IpeakVEM in
channels to adjust the electronic-level trigger.
- Determine the value of QpeakVEM to high accuracy using charge
histograms.
24
25. The calibration is done in 3 main steps:
- The high voltage of each PMT is adjust to have approximately the
same QpeakVEM in each PMT.
- Each PMT has a single rate spectrum. Then we adjust the trigger
thershold to have a single a rate of 100Hz at IpeakVEM = 150 ch.
- This choice sets up each of the PMT to have approximately 50ch /
IpeakVEM.
- Continually perform a local calibration to determine the IpeakVEM in
channels to adjust the electronic-level trigger.
- Determine the value of QpeakVEM to high accuracy using charge
histograms.
25
26. The calibration is done in 3 main steps:
- The high voltage of each PMT is adjust to have approximately the
same QpeakVEM in each PMT.
- Each PMT has a single rate spectrum. Then we adjust the trigger
thershold to have a single a rate of 100Hz at IpeakVEM = 150 ch.
- This choice sets up each of the PMT to have approximately 50ch /
IpeakVEM.
- Continually perform a local calibration to determine the IpeakVEM in
channels to adjust the electronic-level trigger.
- Determine the value of QpeakVEM to high accuracy using charge
histograms.
26
27. The calibration is done in 3 main steps:
- The high voltage of each PMT is adjust to have approximately the
same QpeakVEM in each PMT.
- Each PMT has a single rate spectrum. Then we adjust the trigger
thershold to have a single a rate of 100Hz at IpeakVEM = 150 ch.
- This choice sets up each of the PMT to have approximately 50ch /
IpeakVEM.
- Continually perform a local calibration to determine the IpeakVEM in
channels to adjust the electronic-level trigger.
- Determine the value of QpeakVEM to high accuracy using charge
histograms.
27
28. The calibration is done in 3 main steps:
- The high voltage of each PMT is adjust to have approximately the
same QpeakVEM in each PMT.
- Each PMT has a single rate spectrum. Then we adjust the trigger
thershold to have a single a rate of 100Hz at IpeakVEM = 150 ch.
- This choice sets up each of the PMT to have approximately 50ch /
IpeakVEM.
- Continually perform a local calibration to determine the IpeakVEM in
channels to adjust the electronic-level trigger.
- Determine the value of QpeakVEM to high accuracy using charge
histograms.
28
35. 0
Inclined Showers( >60 ):
The analysis of inclined events is very important
because:
- Increase the statistics, ∈ (600,800), 30% more events.
- Enlarge sky map: allows the study of clustering and anisotropy in an
extended region of the sky.
- EM component is absorbed in the atmosphere. Inclined showers are
sensitive to the muonic component.
- We can study composition, because the total number of muons
depends on the energy and primary particle type.
- Neutrino events may interact deep in the atmosphere.
35
36. 0
Inclined Showers( >60 ):
The analysis of inclined events is very important
because:
- Increase the statistics, ∈ (600,800), 30% more events.
- Enlarge sky map: allows the study of clustering and anisotropy in an
extended region of the sky.
- EM component is absorbed in the atmosphere. Inclined showers are
sensitive to the muonic component.
- We can study composition, because the total number of muons
depends on the energy and primary particle type.
- Neutrino events may interact deep in the atmosphere.
36
37. 0
Inclined Showers( >60 ):
The analysis of inclined events is very important
because:
- Increase the statistics, ∈ (600,800), 30% more events.
- Enlarge sky map: allows the study of clustering and anisotropy in an
extended region of the sky.
- EM component is absorbed in the atmosphere. Inclined showers are
sensitive to the muonic component.
- We can study composition, because the total number of muons
depends on the energy and primary particle type.
- Neutrino events may interact deep in the atmosphere.
37
38. 0
Inclined Showers( >60 ):
The analysis of inclined events is very important
because:
- Increase the statistics, ∈ (600,800), 30% more events.
- Enlarge sky map: allows the study of clustering and anisotropy in an
extended region of the sky.
- EM component is absorbed in the atmosphere. Inclined showers are
sensitive to the muonic component.
- We can study composition, because the total number of muons
depends on the energy and primary particle type.
- Neutrino events may interact deep in the atmosphere.
38
39. 0
Inclined Showers( >60 ):
The analysis of inclined events is very important
because:
- Increase the statistics, ∈ (600,800), 30% more events.
- Enlarge sky map: allows the study of clustering and anisotropy in an
extended region of the sky.
- EM component is absorbed in the atmosphere. Inclined showers are
sensitive to the muonic component.
- We can study composition, because the total number of muons
depends on the energy and primary particle type.
- Neutrino events may interact deep in the atmosphere.
39
40. 0
Inclined Showers( >60 ):
- Inclined showers are all about muons!
- Understand the tank response to inclined muons is
crucial.
- Up to now there is not specific measurements for
inclined and individuals muons with high statistics.
- We only have simulations! Which have some unknown
parameters.
40
41. Muon Flux and Muon rate
in a Pierre Auger Tank
70 deg. -> 1 Hz
80 deg. -> 0.04 Hz 41
85 deg. -> 0.001 Hz
42. Inclined Showers
TODO LIST:
- Charge histograms as a function of the zenit angle
- Direct light (PMT balance)
- Signal versus Track length
- Measured the muon flux
- Muon decay
- Start Time variance
- Check the simulations
42
