# VCI2016 - The 14th Vienna Conference on Instrumentation

Feb 15 – 19, 2016
Vienna University of Technology
Europe/Vienna timezone

## Radiation length imaging with high resolution telescopes

Not scheduled
15m
Vienna University of Technology

#### Vienna University of Technology

Gusshausstraße 27-29, 1040 Wien
Board: 54
Poster Semiconductor Detectors

### Speaker

Mr Ulf Stolzenberg (Georg-August-Universität Göttingen)

### Description

The construction of low mass vertex detectors is of high interest for next generation collider experiments like Belle II. Test beam experiments with multi GeV particle beams and high resolution tracking telescopes provide an opportunity to obtain precise 2D images of the radiation length $X$/$X_0$ of thin planar targets like detector modules. The method developed to measure the radiation length uses hits from the reference telescope and requires no readout of the detector module under study. At the heart of a spatially resolved $X$/$X_0$ measurement is a precise reconstruction of the particle's hit position and scattering angle at the target plane. The main challenges are the alignment of the reference telescope and the calibration of its angular resolution. Systematical uncertainties can be minimized by conducting a calibration measurement, where the module under study is replaced by an aluminium target with a well known thickness profile. In order to demonstrate the capabilities of $X$/$X_0$ imaging, a test beam experiment with the AIDA telescope has been conducted at the DESY test beam facility. The device under test was a mechanical prototype of a DEPFET pixel module for the Belle II vertex detector. A data sample of 25 million tracks at $4\, \mathrm{GeV}$ has been collected with a rate of $700\, \mathrm{Hz}$ within three hours. The data is sufficient to resolve bump bonds below the readout ASICs and to measure the thickness profile of the all-silicon DEPFET module.

### Primary author

Mr Ulf Stolzenberg (Georg-August-Universität Göttingen)

### Co-authors

Ariane Frey (Georg-August-Universitaet Goettingen (DE)) Dr Benjamin Schwenker (Georg-August-Universität Göttingen) Carlos Marinas (University of Bonn) Florian Jochen Lutticke (Universitaet Bonn (DE)) Mr Philipp Wieduwilt (Georg-August-Universität Göttingen)