# The `PSI_Focus` Instrument

*McStas: The FOCUS Spectrometer at PSI (Paul Scherrer Institute,Switzerland)*

## Identification

- **Site:** PSI
- **Author:** <a href="mailto:Uwe.Filges@psi.ch">Uwe Filges</a>
- **Origin:** <a href="http://www.psi.ch">PSI</a>
- **Date:** Jan 2004

## Description

```text
This instrument is a model of the FOCUS Spectrometer at PSI, Villigen, CH.
```

## Input parameters

Parameters in **boldface** are required; the others are optional.

| Name | Unit | Description | Default |
|------|------|-------------|---------|
| lambda | Angs | source energy | 3.4 |
| chopp_ratio | 1 | Chopper radio Fermi Chopper to Disk Chopper | 1 |
| DET | deg | Detector angle | -69.9 |

## Links

- [Source code](PSI_Focus.instr) for `PSI_Focus.instr`.
- Written by U.Filges <uwe.filges@psi.ch> PSI, Jan 2004

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