Status of no-stretch no-spacer GEM assembly. The NS2 Technique

Method and experimental results

Laura FranconiAndrey MarinovRui de Oliveira

On behalf of the GEMs for CMS Collaboration

The NS2 Technique 2

Older techniques

• Thermal stretching and gluing.• Honeycomb method:

The NS2 Technique 3

NS1 and NS2

Readout PCB

Readout PCB

GEMs

GEMs

Drift

Drift

NS1 is relaying on the elastic properties of the periphery frame

The screw is pushing the frame before the stretching.

The screw is pulling out the console

Detector base

Detector Base

4

First prototype: the NS1 (10x10)cm2

The NS2 Technique

Good shape of the pulse height spectrum

Gain up to 3·104 Good uniformity across the entire surface

The NS2 Technique 5

NS2 (30x30) cm2

• The (10x10) cm2 NS2 GEM detector gave excellent results in terms of – Gain – Uniformity across the chamber, indicating that the

stretching is uniform on the whole surface

• These results encouraged us to build the (30x30) cm2 triple GEM detector

The NS2 Technique 6

30x30cm GEM detector based on NS2 technique

A (30x30)cm2 GEM foil before stretching.

The same foil after the stretching, already inserted in the detector’s frame.

The NS2 Technique 7

NS2 (30x30) cm2 – The frame

Drift plane with the pins for the HV connections and a particular of the new Ceramic HV divider.

The Read-out board with labels of the different sectors. Lengths of the different strips are indicated. Strip Pitch = 0.8 cm (in all the surface)

The NS2 Technique 8

• Measurements of the (30x30) cm2 performed in all the sectors with 2 gas compositions:– Ar/CO2 (70/30)

– Ar/CO2/CF4 (45/15/40)

• Chamber irradiated with 8 keV X-rays gun – X-rays generator’s settings: 2mA, 20kV– Collimator diameter

• 2 mm for counts, pulse height spectra, gain calibration and rate capability

• 6 mm for gain stability

NS2 (30x30) cm2 – Tests

The NS2 Technique 9

Rate measurements

The NS2 Technique 10

Pulse Height Spectra

The NS2 Technique 11

Good overlap of the curves relative to different sectors in the same gas composition

Gain Calibrations

The NS2 Technique 12

Gain Stabilities

The NS2 Technique 13

Rate Capability

The NS2 Technique 14

Rate Capability in Time

The NS2 Technique 15

Future Plan

Producing NS2 GE1/1 CMS baseline detector

The NS2 Technique 16

Thank you