Neutron Time of Flight Calculator

Calculator

Example Data Table

The sample values below use a fixed flight path of 4 m.

Formula Used

This calculator uses standard non-relativistic neutron relations for laboratory time-of-flight work.

Time of flight: t = L / v

Velocity from energy: v = √(2E / m)

Energy from velocity: E = 1/2 mv²

De Broglie wavelength: λ = h / (mv)

Timing uncertainty from path spread: Δt(path) = ΔL / v

Total timing uncertainty: Δt(total) = √(Δt(pulse)² + Δt(path)²)

Approximate energy resolution: ΔE / E ≈ 2Δt / t

These equations work very well for cold, thermal, and many epithermal neutron cases.

How to Use This Calculator

1. Choose the calculation mode that matches your known input.
2. Enter the flight path in meters.
3. Provide energy, velocity, or measured time as required.
4. Add optional pulse width and path uncertainty to estimate resolution.
5. Press Calculate to display the result above the form.
6. Review converted outputs, wavelength, uncertainty, and the graph.
7. Use the CSV or PDF button to save the current result set.

FAQs

1. What does neutron time of flight mean?

It is the travel time a neutron needs to move across a known path. Once path length and time are known, velocity and energy can be estimated from standard neutron motion equations.

2. When should I use energy to time mode?

Use it when the neutron energy is already known or assumed. The calculator converts that energy into velocity and then computes the flight time for the path you entered.

3. When is measured time to energy mode useful?

Use it when your instrument gives a direct arrival time. The calculator derives velocity from distance and time, then estimates kinetic energy and wavelength.

4. Does this calculator include relativistic corrections?

No. It uses non-relativistic neutron formulas. That is suitable for many neutron beam applications, but very high energies may need relativistic treatment for better precision.

5. Why is wavelength included in the result?

Neutron wavelength is important in scattering, diffraction, and instrument design. It helps connect time-of-flight values to structure measurements and beam behavior.

6. What do pulse width and path uncertainty do?

They estimate how timing spread affects your measurement. Larger spreads increase time uncertainty and usually worsen the approximate energy resolution reported by the calculator.

7. Can I save the output for reports?

Yes. After calculation, you can download the current result set as a CSV file or a PDF summary for records, sharing, or analysis.

8. Which units are supported here?

The calculator supports meV, eV, keV, and MeV for energy. It also supports ns, µs, ms, and s for measured or pulse timing inputs.