S. E. Tzamarias

The project is co-funded by the European Social Fund & National Resources EPEAEK-II (PYTHAGORAS)The project is co-funded by the European Social Fund & National Resources EPEAEK-II (PYTHAGORAS)

KM3Net Kick-off Meeting, Erlangen-Nuremberg, 11-13 April 2006

HOU Contribution to WP4 (Information & Technology)

Events Generator

•Neutrino (all flavors) Induced Events

•Atmospheric Muon Generation

•Atmospheric Neutrinos•Cosmic Neutrinos (Several Models)

•Neutrino Interactions (use of Pythia)

Example: Earth Absorption

Nadir

Angle

Pro

bab

ilit

y o

f a

ν μ t

o c

ross

Ear

th

Extensive Air Showers

•Production of Secondaries, transportation, energy loss

Example: νe interacting inside a grid-like detector

Monte Carlo Development : Simulation Technique Cherenkov photon emission

A new, very efficient, general purpose, Cherenkov simulation algorithm

find the center of mass m1 of group1

find the center of mass m2 of group2

Define 2 points inside the detector, p1 & p2

For all PMTsWhich point is closer ?

p1 p2

Add PMT to group1 Add PMT to group2

is m1=p1 and m2=p2

yes

no

converge

Stage 1:Define PMT clusters according to the detector geometryStage 2: Use the Clusters for the Cherenkov photon production

The simulation strategy is applicable and efficient for any detector architecture without

any extra optimization

Monte Carlo Development : Simulation of the Detector Response (GEANT4)

Angular Distribution of Cherenkov PhotonsEM Shower Parameterization

Parameterization of EM Shower

•Longitudal profile of shower

•Number of Cherenkov Photons Emitted (~shower energy)•Angular profile of emitted photons

General purpose:

Simulation of (any) PMT Response

Simulation of electronic functions

mV

Simulation Example

1 TeV Vertically incident muon

K40 Noise Hits

Signal Hits

(Hit amplitudes > 2p.e.s)

Computer Power

•Computer Farm with 15 computers (15 double xeons )

•We are currently installing 64 more computers (64 double opterons)

350 Gflops

Current Studies

• PMT orientation and photon directionality

• nested vs uniform architecture for ~1TeV muons

• fast triggers and filtering algorithms

• detector calibration using EAS

Fast Triggering Algorithms

Estimation of Information Rate

1km3 Grid (18522 15inch PMTs)

Information Rate = PMT Number * K40 Noise Rate * (Bytes/Hit)

= 18522 * 50kHz * 32

≈ 30GB/sec

Cannot be saved directly to any media

Charge & Multiplicity Characteristics

Charge/hit distribution

Number of pes

noise

signal

Multiplicity (signal)

Multiplicity (noise)

Number of active PMTs in 6 μs window

Number of active PMTs in 6 μs window

No Cut

1TeV Vertical Muons

Charge & Multiplicity Characteristics

Selection based on hits with at least 2 photoelectrons

Multiplicity (signal) Multiplicity (noise)

Information Rate = PMT Number * K40 Noise Rate * (Bytes/Hit)

= 18522 * 3kHz * 32

≈ 1.8GB/sec

By Using clustering like DUMAND the background rate is reduced by 75% (450 MByte/sec) and the signal hit has a higher than 60% probability to survive

Fast Triggering Algorithms

Estimation of Information Rate

1km3 Grid (18522 triplets of PMTs)

3 PMTs per hemisphere in coincidence

10nsec time window, 2 out of 3 coincidence

Each triplet’s total photocathode = 15inch PMT photocathode

Information Rate = PMT Number * K40 Noise Rate * (Bytes/Hit)

= 3* 18522 * 17 Hz * 32

≈ 30MB/sec

Triplet coincidence rate=17Hz (17kHz background per PMT)

Number of active triples

Background

Signal

1TeV Vertical Muons

Fast Triggering Algorithms

Use of the number of activate triplets as fast selection trigger

Distributions normalized to 1

Fast Triggering Algorithms

Estimation of Event Rate and Efficiency

Eve

nt R

ate

(kH

z)

Cut to the number of active triplets

Eff

icie

ncy

Cut to the number of active triplets

180 kByte/event

10TeV

1TeV

Fast Triggering Algorithms

1TeV Vertical Muons

Use also the Dumand clustering:

Background

Signal

Number of active triples

Fast Triggering Algorithms

Estimation of Event Rate and Efficiency

Eve

nt R

ate

(kH

z)180 kByte/event

Cut to the number of active triplets

Eff

icie

ncy

Cut to the number of active triplets

1TeV

Fast Triggering Algorithms

Raw Hits

Absolute time

TimeStretching

Trigger Level

trigger

Accepted Interval

Triggering Method

36 PMs in 3 subcylinder

35 3” photomultipliers in a cylinder

Determination of photon direction, e.g. via multi-anodic PMs plus a matrix of Winston cones.

Large photocathode area with arrays of small PMTs packed into pressure housings

Alternative Options for photodetection

t1

t2

t3Ethernet

A. Leisos

H.O.U., Univ. Athens, Univ. Patras, INP DEMOKRITOS, NTUA

A StationGPS

ScintillatorScintillator

PC

~20 m

TCP/IP

ScintillatorScintillator

A. Leisos

Eurocosmics

The General Idea…

•Angular offset

•Efficiency

•Resolution

•Position

•Detector calibration using EAS