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Tank Calibration Pierre Auger Observatory

Gonzalo Rodriguez Universidad de Santiago de Compostela

Astroparticle groupfor the Pierre Auger Collaboration

Trasgo Project

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• 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.

Pierre Auger Observatory research goals

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• 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?

Pierre Auger Observatory research goals

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Not only muons hit the tank!!!!

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Event reconstruction: S(1000m)

S(1000m)S(1000m)

1000m1000m

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)

Slope β fixed

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Fluorescence Reconstruction

SD tank

- Fluorescence energy almost MC independent.

EFD

= finv

x Eem

Electromagnetic energy

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VEM: Vertical Equivalent MuonThe Cherenkov light is measured in units of the signal produced by a: Vertical and Central Through-going Muon.

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VEM: Vertical Equivalent MuonThe 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 2500Hz1 minute ~ 150000 events

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Tipical FADC traces150000 triggers

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Tipical FADC traces150000 triggers

Pulse height - Ipeak

VEM

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Tipical FADC traces150000 triggers

Pulse height - Ipeak

VEM

Charge = Sum FADC(i) - Qpeak

VEM

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Charge histograms and their relation to a VEM trigger threshold 0.2Ipeak

VEM

For the sum of the 3 PMTs Qpeak

VEM = 1.09 VEM

Individual PMTsQpeak

VEM = 1.03 VEM

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From simulations we can understand the charge histrograms structure

Particles Flux Charge histograms

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From simulations we can understand the charge histrograms structure

Particles Flux Charge histograms

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The calibration is done in 3 main steps:

- The high voltage of each PMT is adjust to have approximately the same Qpeak

VEM 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 Ipeak

VEM = 150 ch.

- This choice sets up each of the PMT to have approximately 50ch / Ipeak

VEM.

- Continually perform a local calibration to determine the Ipeak

VEM in

channels to adjust the electronic-level trigger.

- Determine the value of Qpeak

VEM to high accuracy using charge

histograms.

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The calibration is done in 3 main steps:

- The high voltage of each PMT is adjust to have approximately the same Qpeak

VEM 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 Ipeak

VEM = 150 ch.

- This choice sets up each of the PMT to have approximately 50ch / Ipeak

VEM.

- Continually perform a local calibration to determine the Ipeak

VEM in

channels to adjust the electronic-level trigger.

- Determine the value of Qpeak

VEM to high accuracy using charge

histograms.

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The calibration is done in 3 main steps:

- The high voltage of each PMT is adjust to have approximately the same Qpeak

VEM 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 Ipeak

VEM = 150 ch.

- This choice sets up each of the PMT to have approximately 50ch / Ipeak

VEM.

- Continually perform a local calibration to determine the Ipeak

VEM in

channels to adjust the electronic-level trigger.

- Determine the value of Qpeak

VEM to high accuracy using charge

histograms.

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The calibration is done in 3 main steps:

- The high voltage of each PMT is adjust to have approximately the same Qpeak

VEM 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 Ipeak

VEM = 150 ch.

- This choice sets up each of the PMT to have approximately 50ch / Ipeak

VEM.

- Continually perform a local calibration to determine the Ipeak

VEM in

channels to adjust the electronic-level trigger.

- Determine the value of Qpeak

VEM to high accuracy using charge

histograms.

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The calibration is done in 3 main steps:

- The high voltage of each PMT is adjust to have approximately the same Qpeak

VEM 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 Ipeak

VEM = 150 ch.

- This choice sets up each of the PMT to have approximately 50ch / Ipeak

VEM.

- Continually perform a local calibration to determine the Ipeak

VEM in

channels to adjust the electronic-level trigger.

- Determine the value of Qpeak

VEM to high accuracy using charge

histograms.

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Information about Calibration that comes with each event

Baseline Histogram

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Information about Calibration that comes with each event

Pulse Height Histogram

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Information about Calibration that comes with each event

Shape Histogram

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Information about Calibration that comes with each event

Charge individual PMT Histogram

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Information about Calibration that comes with each event

Charge sum of 3 PMTs Histogram

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Sig

nal

[V

EM

pea

k]

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Inclined Showers( >600):

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.

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Inclined Showers( >600):

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.

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Inclined Showers( >600):

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.

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Inclined Showers( >600):

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.

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Inclined Showers( >600):

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.

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Inclined Showers( >600): - 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.

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Muon Flux and Muon rate in a Pierre Auger Tank

70 deg. -> 1 Hz80 deg. -> 0.04 Hz85 deg. -> 0.001 Hz

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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