Radioactive Decay & Detector Lab

Switch between decay-law, counting, detector, and reaction modes to keep exponential trends, background subtraction, and measurement context aligned.

GCE A-Level H2 Physics 2027

Learning goals

Analyse random radioactive decay, activity, decay constant and half-life.
Apply conservation laws to nuclear equations and beta decay, including antineutrino evidence.

Loading the interactive model…The interactive model did not load. Try again reloads this page; the explanation and worked content here are still available.

Change one variable at a time and watch the model respond.

Lab setup

Main mode

Nuclear task

Source isotope

Elapsed time since the start12 h

Detector setup in the scene

Detector distance from source6 cm

Data view and options

Options

Evidence view

Include background countsShow deterministic noisy dataShow hints during prediction

Practice run

Choose a mode and checkpoint count when you want scoring.

Run modeGuidedChallengeTest

Run length

Try Nuclear Physics Quiz

Choose your checkpoint count for guided or challenge mode.

Study lensUse half-life, decay constant, activity, and exponential-decay relationships with the correct physical quantity and time unit.15 min activity

Try this

Name the quantity first: activity, measured count rate, background, or net source count rate. Then do the subtraction or decay step.

Learn to

Use half-life, decay constant, activity, and exponential-decay relationships with the correct physical quantity and time unit.
Separate measured count rate, background count rate, net source count rate, and source activity in detector questions.
Compare detector readings and classify nuclear reactions without reducing every change to distance alone.

Exam transfer

Decay data
Detector measurements
Reaction classification

Governing idea

Corrected count rate = measured count rate − background count rate. For a compact source far from the detector, count rate is approximately proportional to 1/r².

Model boundary

Counts fluctuate statistically and the geometry, detector efficiency, dead time, and absorption are simplified. The inverse-square trend is only approximate near the source.

Avoid this trap

Background is part of every measurement and must be estimated and subtracted; one short count is not an exact activity reading.

How to explore

Work through decay law, background correction, detector readings, and nuclear reactions with realistic noisy count data.

Predict the outcome, change one variable at a time, then interpret the result. Completion records participation only and does not award mastery.

About this activity

Switch between decay-law, counting, detector, and reaction modes to keep exponential trends, background subtraction, and measurement context aligned. A text explanation and no-JavaScript route remain available.

How this activity affects progress

Course and syllabus information

Course: GCE A-Level H2 Physics
Edition: GCE A-Level H2 Physics 2027