# Setting of the predefined multiplier gain of a photomultiplier

## TL;DR

This paper presents an automated method for precisely setting the gain of photomultiplier tubes with minimal operator involvement, achieving up to 2% accuracy, demonstrated on 2000 PMTs for the Borexino detector.

## Contribution

It introduces a new automated gain adjustment method that ensures high precision with minimal manual intervention for large PMT arrays.

## Key findings

- Achieved gain setting precision up to 2%.
- Successfully applied to 2000 PMTs in Borexino.
- Reduces operator involvement in PMT calibration.

## Abstract

A method to set the predefined PMT gain with high precision is described. The method supposes minimal participation of the operator. After the rough initial setting of the gain, the automated system adjusts the PMT gain within a predefined precision (up to 2%). The method has been successfully applied at the Borexino PMT test facility at LNGS for the gain adjustment of the 2000 photomultipliers for the Borexino detector