observation of bioluminescence in antares j. brunner
TRANSCRIPT
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