Autonomous Rate Measuring System

gilamonsterbirdsElectronics - Devices

Nov 24, 2013 (3 years and 6 months ago)

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Autonomous Rate Measuring System




Theodoros Athanasopoulos

Representing the KM3NeT Consortium

Nestor Institute For Astroparticle Physics


VLV
v
T09

Athens 13
th



15
th

October 2009



13/10/2009

VLVvT09 Theodoros Athanasopoulos

1

Autonomous Rate Measuring System


Target of the experiment


To measure the effect of sedimentation and bio
-
fouling on the
glass surface of optical modules deployed in the deep sea.


How do we measure?


We will periodically measure and record the singles at ½ spe
and doubles (in a 10ns window) PMT rates caused mainly by
K
40

decays and monitor the gain by recoding the single
photoelectron pulse height.




13/10/2009

VLVnT09 Theodoros Athanasopoulos

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Autonomous Rate Measuring System

An Autonomous System

The PMT Rate Measuring System is an autonomous system, battery powered,
designed to operate for more than 1 year with data recorded in memory and
monthly transfers acoustically to surface. Due to limited battery life of the
acoustic modem, data transmitted has been designed to be only 40kB per month.

Battery life is also an issue for the rest of the electronics so low power electronics
have been designed and developed for this system.


The system will be in sleep mode most of the time. It will turn on only for 1 hour
every week to take the measurement, store the data and go to sleep mode again.
It will also wake up to transmit the data upon acoustical request.


System total power consumption is:

On Mode: 40W

=> 40W x 52h = 2080Wh


Total power consumption = 3219Wh

Off Mode: 130mW => 130 x 8760h = 1139Wh
Total power supplied = 8400Wh






Use of alkaline batteries


13/10/2009

VLVnT09 Theodoros Athanasopoulos

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System Description (Mechanical)

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VLVnT09 Theodoros Athanasopoulos

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APPARATUS LAYOUT (Side View)

Battery bank x 4

8 Optical Modules (4 pairs
)

8ch HV Control

System Description (Electronics)

13/10/2009

VLVnT09 Theodoros Athanasopoulos

5

OM
1

OM
2

OM
3

OM
4

OM
5

OM
6

OM
7

OM
8

4 Channel
Discriminator
MAX964

4 Channel ADC
AD7476

4 Channel
Discriminator
MAX964

4 Channel ADC
AD7476

FPGA

Spartan
3E

SD

1GB

μ
Controller

PIC18F4550

Slow
Controls

Power Regulation
&

Power Distribution
System

Board to FPGA buses

8ch HV Monitor

Acoustic Modem

14bit bus

Assembled System

13/10/2009

VLVnT09 Theodoros Athanasopoulos

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Power Regulation and Power Distribution Unit

FPGA Board

Front End Electronics

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VLVnT09 Theodoros Athanasopoulos

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Discriminator

½ SPE

AMP

Peak and Hold

To Singles Rate

Counter

ADC

PMT Pulse

Inverted and

amplified PMT

Pulse

Discriminator

Pulse

Coincidence
Logic

To Doubles Rate

Counter

From Other

Discriminators

Conclusion

We have designed a low power autonomous system to
measure the K
40

rate to stay in the sea for more than
one year. It will be sensitive to reductions in the singles
and doubles rate at single photoelectron conditions
due to sediment adhesion.

Data will be retrieved periodically acoustically.

Expected deployment end of this month. System is
currently being tested at the Nestor Lab.

13/10/2009

VLVnT09 Theodoros Athanasopoulos

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