# disk_to_disk_solid_angle: Calculate fractional solid angle for disk to disk In radsafer: Radiation Safety

## Description

Returns fractional solid angle for a geometry frequently encountered in health physics analysis of air samples or disk smears. This is useful in correcting configurations that do not exactly match calibration (by ratioing the respective fractional solid angles). While units of steridian are used for solid angle, this function only uses a fraction of the total field of view.

## Usage

 ```1 2 3 4 5 6 7 8 9``` ```disk_to_disk_solid_angle( r.source, gap, r.detector, plot.opt = "n", runs = 10000, off_center = 0, beep = "off" ) ```

## Arguments

 `r.source` source radius (all units must be consistent) `gap` distance between source and detector `r.detector` detector radius `plot.opt` plot options - "2d", "3d" or "n". `runs` Number of particles to simulate. Running more particles improves accuracy. Default = 1e4. `off_center` measure of eccentricity between the center of the source and the center of the disk. This is applied to the x-dimension of the source. `beep` Set to "on" if desired. Default is "off". Alerts to end of run if runs is set to a high number.

## Value

Fractional solid angle and plot of simulation.

## References

Other rad measurements: `air_dens_cf()`, `neutron_geom_cf()`, `scaler_sim()`, `tau_estimate()`

## Examples

 `1` ```disk_to_disk_solid_angle(r.source = 15, gap = 20, r.detector = 10, plot.opt = "n", runs = 1e3) ```

### Example output

```   mean_eff         SEM
0.04284274 0.006432702
```

radsafer documentation built on April 13, 2021, 1:06 a.m.