Proposal to Chicago for Cosmic Ray Detector at Millennium Park
9th April 2009based on a presentation prepared by D. Schinzel 1 COSMIC RAY DETECTOR.
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Transcript of 9th April 2009based on a presentation prepared by D. Schinzel 1 COSMIC RAY DETECTOR.
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9th April 2009 based on a presentation prepared by D. Schinzel
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COSMIC RAY DETECTOR
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PLAN OF TALK
– 1 Background of idea – 2 Background on muons– 3 General design plan– 4 Things to start doing
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• The idea arose because we saw one of these at CERN when we visited last year
• It is a device that demonstrates a bit of physics and engineering, but is also an attractive display to impress visitors (and ourselves)
• It will be hard to build because we don’t even have a complete design (yet), let alone all the smaller details
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• Cosmic ‘Rays’ are actually mostly high energy protons hitting the upper atmosphere
• They produce a ‘shower’ of other sub-atomic particles, but especially fundamental particles called muons
• Muons are a kind of ‘heavy electron’• The really interesting thing about
muons is…
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• The really interesting thing about muons is…
• They are unstable, with a half-life of only about 2 microseconds – which means they can’t reach ground level
• But they can reach ground level!• They live much longer than normal
because for them time is passing very slowly due to their very high speed
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• The detector will be a very large spark detector
• You need some metal plates with a high voltage on them, and a chamber filled with noble gases – helium and argon
• Then, if a muon comes along, it may cause breakdown of the gas, and a spark is formed – with dramatic effect!
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• The 4 main things to build or obtain are:– The chamber– Source of noble gas with controls– HT supply – 10kV– Electronics to supply the energy for the
sparks, but also to quench them quickly
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• We’ll buy the – Noble gas and pump and fittings– HT supply – 10kV
• We’ll build the – Chamber – hard to do well – low leakage– Electronics – a lot more detail needed
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• Budget:– The absolute outside cost of the project
is £7,000, but I expect to do it for much less
– I don’t yet have a target budget, so that’s a task to be done, but to give you a feel for it, the HT supply may be the single most expensive part, and one could be bought second-hand for about £650
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• Mode of operation:– Two devices called scintillators detect a
muon coming in– Electronics produces a turn-on pulse,
sent to…– A special device called a ‘thyratron’
which enables a spark to occur– The spark’s energy is released from
some high voltage capacitors
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• Trigger Electronics • HV Pulser
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COSMIC RAY DETECTOR
• Top scintillation counter S1
• Trigger electronics
• Bottom scintillation counter S2
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• Roles to fill– Project management– Financial management– Mech design and build– Electronic design and build– Gas know-how and procurement– Publicity via website, assemblies etc
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• First tasks – for discussion– Visit Bristol Univ to collect more info and some
scintillators– Visit e2v to see what they can offer us– Produce a draft budget and project plan– Design and build a very small proof-of-principle
chamber and test for gas-tightness*– Design and build the low voltage trigger
electronics and connect to scintillators*– Find out how to buy or make the HT resistors
and capacitors– Find out about thryatrons* please note – the D&T dept are aware of the project but are unlikely to
be able to give much in the way of workshop time due to other commitments
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• No Spark • HV = 2.65 kV
• Trigger given by scintillators S1 and S2
• Thyratron discharges capacitors, then they recharge
• Dead time
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• Spark • HV = 4.5 kV
• Trigger
• Spark discharges capacitors
• Dead time
COSMIC RAY DETECTOR