Experimental TechniquesNick Esker

Postdoc, EMMA group

neesker@triumf.ca

Three sessions for all detection schemes…..

• My Goal: This is a very large area of active research, with ~100 years of history from Roentgen & the Curies to present. I want you all to be able to tackle a modern experiment without getting too distracted / off-put by the “how”

• Three sessions IS NOT ENOUGH!!!! I’m purposefully ignoring:• Accelerators, reactors

• Relativistic effects

• Electronics / DAQ

• Statistics

How this’ll work

• We’ve a lot of material to cover. Too much.

• I’m a strong believer in “active learning”• 40-50 min of lecturing (with plenty of questions )

• 10-15 min of small group activity, working on some toy problems

• PLEASE ASK QUESTIONS!!!!

• Resources:• Knoll: Nuclear Instrumentation

• Krane: Nuclear Physics

The PlanTM

Day 1 – Nov 6• Radiation interaction

with matter• α, β, γ, n0 , SF decay

• Scintillators• Organic

• Inorganic

• Light detectors• PMT, MCP

• Examples at TRIUMF

Day 2 – Nov 15• Charge particles

counting w/ gas• Geiger-Mueller

• Prop. counters

• Semiconductors• Si detectors

• HPGe detectors

• Examples at TRIUMF

Day 3 – Nov 17• Manipulating matter

• E and B fields

• lasers

• Examples• Recoil separators

• Traps

• Potpourri• Active targets

• 0νν detectors

• HE calorimeters

Ionizing radiation’s interaction with matter

• Sources of ionizing radiation?• Accelerators and Reactors (& HE lasers)

• Multiple secondary sources

• Nuclear decay• α, β, γ, n0 , SF decay

Nuclear decay

• α

• β

• γ

• n0

• SF

Nuclear decay

“Heavy” charged ions

10 MeV / u, Zbeam= 6,7,8,10,18

“Heavy”, charged ions

• Bragg Curve

• Energy (E), range in matter (x), and timing (t) are all affected by straggling, which widen their distributions

Believing Bragg by Bethe-Bloch

Beyond heavy…

• e-

Photons and matter

Photons and matter

• Three regimes

n0 interactions

• Elastic collision with the nucleus• Capture cross section dependent

• Look for secondary forms of radiation

E deposited in matter

• So, at this point, we’ve covered a couple general ways to deposit E of our ionizing radiation into some material. Once it’s there, how can we detect it?

Scintillating

• What makes a good scintillator?

Scintillators

• Organic

• Inorganic

Efficiency of scintillation

Detecting Light - PMT

Detecting Light - MCP

Concluding remarks

Active scintillators @ TRIUMF

• DRAGON’s gas target

Active scintillators @ TRIUMF

• DESCANT neutron detectors

Exercise

1. Calculate the scintillation efficiency of anthracene if a 1.5 MeV alpha particle is stopped in the medium, which created 20,300 photons with average wavelength of 447 nm

2. Starting from the full Bethe-Bloch, derive the non-relativistic Bethe-Bloch from the lecture

3. An ion chamber with parallel plate electrodes, spaced 5 cm apart, is filled with methane up to 1 atm and operated at 1 kV. Knowing the W-value of methane (27.3 eV/ ion pair), calculate the maximum e collection time. (Might need to look up mobility of ions in electric field, gas)