Observation of Bioluminescence in ANTARES

J. Brunner

Counting rate of 3 PMTs from ANTARES

• Taken this morning - 2 min sample• Sampling 100 msec• Baseline: radioactivity + bacteria• “bursts”: macroscopic animals

Real events from PMT versus literature

Examples of bursts

Median rate 5 years

• Monitoring of average activity

• One measurement every 15 min

Spring 2006 Spring 2009

Cameras on IL07

• Cameras on floor 1 and floor 5 together with an OM and an ADCP

• Floor 1 – 2400 m below surface– 80m above sea floor

• Floor 5– 2200 m below surface– 270m above sea floor

Installation on IL07

Motivation - Specifications

• Observation of deep sea bioluminescence in its natural environment

• Observe deep sea fauna undisturbed by noise or light (ROVs, Wallys, etc.)

• Self triggering system to avoid tons of black images (“event recognition”)

• Automatic data transfer to shore station• Light source to reveal origin of light flash• Correlation of images with PMT counting rates

Camera

AXIS221 vidéosurveillance

Night view capabilitiesView field up to 90 degreeSensitive into infraredView field & focus can be set manuallyDiaphragm & exposure time automatically / remotely controlled

Data outputEthernet

Power 12-24V, 5WControl of external device

IR Source

Absorption in water less than 1m – no interference with PMTs on other lines

~60 LED 850nm

Can be controlled (switched ON/OFF) by camera

Mechanics & Electronics @ CPPM

Test setup for water testsFinal mechanics frame to hold cameraAnd IR source (not yet mounted)

Mounting on OMF (floor 5)Try to maximize overlap of field of view between camera and OM

Combined tests with ISIT

ISIT IR AXIS

ISIT : intensified silicon intensifier tubeUniversity Aberdeen 1995, 20,000 EuroClaimed sensitivity ~ 10-6 lux

Bacteria sample

Test with laser

laser

OMSplitter16x

Diffuser

Geometrical factor 0.1

Cameralens

100-1000 Hz

Integration variable

1cm2

Test with laserAXIS 1sec AXIS 1/25sec ISIT 1/25 sec

3.10-5 lux

3.10-6 lux

ISIT ~ factor 20 more sensitive ; AXIS better resolutionMissing sensitivity can be compensated by longer exposure timeWorst case scenario : isotropic light (as from K40)PMT 1MHz = 108 photons/m2/sec = 3 10-8 luxExpect to see pointlike signals at few MHz depending on geometry

Dec 2007 July 2007

Floor 5Floor 1

ADCP

Camera

OM

ADCP

Camera

OM

Early image 2sec exposure

3 sequences of 2 images: 100msec exposure each

3 sequences of 2 images: 100msec exposure each

4 examples of short flashes (visible only on a single image of 100 msec)

4 examples of short flashes (visible only on a single image of 100 msec)

Passing object illuminated in IR light

Small bright object

Extended object

Summary• Successful data taking for almost 3 years• Deepest online cameras in the world• Active more than 90% of time• More than 1000 triggers accumulated• Full analysis pending, many options

– Pattern recognition– Event classification– PMT-camera correlation– Correlation with other environment data:

• Current, temperature, salinity

Next Step: New technology camera deployedSee next talk