Photo story of the construction of the NA62 straw spectrometer

The assembly of the NA62 straw chambers has now completed following an intense R&D programme between CERN and the Joint Institute for Nuclear Research (JINR) in Russia. The team developed new techniques for constructing and assemblying the straws in the four chambers of the experiments and developed the electronics that will be used for reading out the data. It is important for straws to withstand the high vaccumm pressure exerted once they are placed inside the experiment’s vacuum tank and to remain leak-proof in order to preserve the vacuum. Following the successful tests of a prototype of the detector that was based on the same technology and principles, the PH-DT finsihed the production of the straw chambers for the straw spectrometer of the NA62 experiment. The following pictures show the steps taken from the early phases of R&D up to the installation of the straw chambers in the NA62 tracking detector.

The straws were manufactured by ultrasonic welding with the seam in the axial direction. The image shows a detail of the straw welding machine

A microscopic image showing the cross-section of the weld.

Ageing tests with a small two-straw prototype.

Construction of the prototype straw detector by PH-DT in 2009.

Testing the first prototype in a beam line in 2010.

During the installation a tension of 1.5 kg is applied on each straw before gluing them.

A series of plastic rings glued to two metallic wires keep the straws in position inside the chambers.

Thin ULTEM rings glued to a tensioned 0.1 mm metal wire keep the straws straight and in nominal position.

Straw assembly in the chamber support in 2012.

The distance between straws is measured with a high-precision laser. If the distance is too big (bent straw) the straw is replaced.

A view of the far end of the straw chamber after wiring.

Straw-end connectivity and the gas manifold. A flex-rigid circuit board connects the high-voltage to the wire and transmits the signal to the front-end electronics.