Month: May 2023

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First Steps for CHAOSJunior Balloon Experiment

From September 25 to 30, 2023, the science festival “Highlights der Physik” will come to Kiel. As part of this event, we plan to fly a weather balloon with a CHAOSJunior experiment. This consists of a small hexagonal bismuth germanium oxide scintillator (BGO) with two photodiodes glued on opposite sides and two segmented solid state detectors (SSDs), which were adopted from the High Energy Telescop (HET) experiment. These HET-B detectors are placed in front of and behind the BGO and are used for coincidence measurements. In the past weeks, two photodiodes were glued to the BGO on opposite sides. The so prepared BGO was wrapped today in such a way that the light generated in the BGO is reflected on all inner sides and reaches the diodes. This BGO with diodes will be first tested in an already existing test can the following days. In the meantime, a pre-amplifier board for the flight is soldered and connected to the BGO diodes and the HET-B detectors. Then this setup will be tested.

BGO wrapped in teflon tape and put into old casing from HET
BGO with case and other BGO in testbox
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Revival of an old Detector

The proposed CHAOS instrument needs a fairly large area Solid State Detector (SSD). All Detectors that we can use are spare parts from earlier space missions. For this large area SSD we put our eyes on a couple of recently rediscovered Soho Costep EPHIN F-Detectors, manufactured in the 1980ies.

A quick test revealed that all but one of them have excessive bias currents. The one good detector, unit F2, was subject of a C-V measurement, Capacitance versus bias Voltage. That kind of measurement tells about the impurity concentrations (dopands) and thickness of the detector.

The results confirm that the detector is about 700µm thick, and needs about 150V bias to be fully depleted, which is in range with the expectations. The diameter of the SSD is about 8cm.

This EPHIN F2 detector may become the anticoincidence counter of CHAOS. Currently it is tested in operation with cosmic muons and a gamma ray source.

C-V test instruction
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Chaos Server

Welcome to the internet presence of the Chaos project. For the next two years you will find updates of the project in this place. The server is a virtual maschine provided by netcup.de.