Status Report of activities in LNF Soldering procedure 1.Status of soldering machine 2.Measurement of wire position Chamber prototypes 1.Construction of

Status Report of activities in LNF

• Soldering procedure1. Status of soldering machine 2. Measurement of wire position

• Chamber prototypes1. Construction of new prototypes2. Possibility of opening the chambers3. Status of mould4. Mini-ageing test

• Chamber panels and quality control1. Planarity measurements2. Frame height respect to cathode3. Radiation resistance4. Thermal resistance

LHCb Muon meeting – CERN Jan 30, 2002 (C.Forti, A.Saputi)

Soldering machine

1. Status of the setup• Final mechanics ready (see pictures)• One head completely assembled and operational• Labview software (IMAQ of National Instruments) for soldering

and automatic wire pitch measurement under preparation (~ 15 days required)

2. Short film

3. Next steps• Soldering tests on larger scale (up to 150 cm)• 2nd head (ready in ~ 2 months)• Study of the possibility to determine automatically the soldering

quality using reflection of light.

Soldering test

Soldering test

Control of wire positions

A frame wired at CERN was transferred on a “dummy” chamber.

We compared the measurements of the steps between 140 contiguous wires, from a set of 140 soldered wires (139 steps), obtained from the camera of the soldering machine (in pixel) and from an independent optical measurement (in micron).

We found the best conversion factor: 12.5 micron/pixel.We converted the camera measurements from pixels to micronsand compare the two measurements (in micron).

Conclusions:

1. Excellent agreement between analog and digital measurements:• the 2 methods show the same RMS;• RMS of difference analog – digital = 17 microns;• then we can estimate RMS of digital measurement ~ 12 m

2. Only one wire over 140 is in bad position (easily identified).

Step between wires: conversion from pixel to micron

The ratio analogic/digital has a very small RMS 0.09 micron/pixel !!

Step between wires: analogic vs. digital measurement

Step between wires: comparison of analogic and digital

mean

RMS

mdig 122

17

22

1 anawire

22

2 digwire

digana 21

Step between wires: difference analogic - digital

22diganadiff

dig2

mdig 122

17

Construction of chamber prototypes

3 quadrigaps wired at CERN (10-20th december)(each of area ~ 28x34 cm2 n.tot wires=1920)

2 of them have been tested and assembled:• each single gap (without cover) tested at HV=3.2 kV in air: current is 0 nA• assembled (not glued yet) and tested at 3.0 kV (no current)

Wires of third quadrigap are being currenlty soldered (ready in few days).

Including the quadrigap previously constructed, we will have a total number of 2560 wires, equivalent to one large chamber.

Up to now: no wires brokenno HV problemsnever current going up

These prototypes were very helpful in understanding construction procedures and HV critical tests.

Test on possibility of opening the chambers

As you know, Frascati approach is to use glue for closing the chambers.

We are considering the possibility of opening the chambers in case of malfunctioning, using a circular cutter to remove the glue (see drawings).

The conclusions of a first test are encouraging:

• the operation is easy;• it is easy to re-close the chamber (usual gluing procedure);• the cutter will be provided with a exhaust fan (low dust);• short time needed: few minutes.




Status of the new mould (big one)

Mould for M3R3 chamber: • the company has straightened the mould planes (in Al alloy);• within a few days, the mould contruction will start (about 20 days required);• then, we will start production of large panels (150 x 40 cm2)

1500 mm

500

mm

Ageing test with X rays

A B C D

5.9 keV X ray

Gaps A and B @ 3300 V, irradiated for 1 month (21 dec-21 jan). They were always on.We monitored the currents in gaps A and B

5 A 15 nA

Dose = 5.7 A x 30 days = 14.8 CoulombThe irradiated zone was too large = 3x3 cm2. So we have ~ 65 cm of wires irradiated.Dose/cm of wire ~ 0.23 C/cm of wire, corresponding to :4.6 LHC years equivalent in M1R3 or M2R1while a 10 years test is necessary.

Ageing test with X rays: currents

Relative variation of currents, in gap A (TOP)and B (BOTTOM) in onemonth of test (~ 720 h).

Currents always wentto 0 when switched off

Gap A was stable over this period.

The behaviour of Gap B is not well understood. The current was too low and gap B could not to be used as reference.Attenuation from A to B was ~ 300, while ~ 10 could have been OK.

Our ageing test is encouraging, even if not conclusive: the currentin Gap A (at 3.3 kV) is stable over one month of test, equivalent to~ 4.6 LHC years.

There is the possibility to perform a complete ageing test, using the Co60 source at ENEA-Casaccia. The distance of the detector from the Co60 sources can be changed to tune the current drawn in test and reference detectors.

However, this test is expensive: negotiacions are pending.

Ageing test with X rays: conclusions

Chamber panels

Total number of panels produced: 52 panels (28 x 34 cm2) Now, we check systematically the panel quality (from last 22 panels produced)

• Measurement of planarity1. all panels measured, just after delivery2. 2 panels: after thermal stress (oven and/or refrigerator)3. 3 panels: after radiation stress (gammas of Co60 source)

• Height of HV bar respect to cathode

• Tests of fire resistance are being performed by italian fire corps

• Mechanical tests (Will be performed in Potenza in the first half of february)

1. Flatwise tensile strength (ASTM C297)2. Flatwise compressive properties of sandwich cores (ASTM C365)3. Flexural properties of sandwich constructions (ASTM C393)4. Facing cleavage of sandwich panels (ASTM E2004)

PANEL TYPE PRODUCTION DATE DESTINATION

1 PAD 30-NOV-01 PROTOTYPE CONSTRUCTION



4 GROUND 30-NOV-01 PROTOTYPE CONSTRUCTION









13 PAD 4-DEC-01 PROTOTYPE CONSTRUCTION

14 GROUND 4-DEC-01 OVEN (70 C) + MECHANICAL TEST

15 GROUND 4-DEC-01 PROTOTYPE CONSTRUCTION

16 GROUND 4-DEC-01 PROTOTYPE CONSTRUCTION

17 GROUND 12-DEC-01 RADIATION TEST (10**4 Gray)


19 GROUND 12-DEC-01 MECHANICAL TEST

20 GROUND 12-DEC-01 MECHANICAL TEST

21 GROUND 12-DEC-01 OVEN (40 C) + MECHANICAL TEST


Planarity measurement: method

• From a set of measurements(x,y,z) defines a reference plane

• For 65 (x,y) values,measures the distance of the point from the plane

• 16 points belong to panel border and show larger deviations from the reference plane

Planarity measurements: all panels together

~ 1800 points measured

For each panel, if we exclude the points nearest to the border (at ~ 18 mm from it),we get RMS=16.6 With the border included we get RMS=26.9

Planarity measurements: best panel (n.18) GROUND

Side 1

Side 2

4 panels with framesFor each panel we measured12 points (6 on each side)

glue

HV bar

panel

Precise bar

2.49 mm

Check of HV bar positioning

Frame height respect to the cathode

Well within specs

Could be better with a rectified bar

Radiation test at ENEA Casaccia (near Rome) with a powerful Co60 source E=1.25 MeV; the source can operate at 104 Gray/hour = 1 Mrad/hour.

We chose to irradiate 3 panels at ~80 cm of distance (400 Gy/hr), because a smaller rate causes a bigger damage in polyurethane (Schonbacher and Tavlet, CERN).Test duration ~ 25 hours Total ionising dose ~ 104 Gray.

Radiation test setup

Radiation effect on planarity: panel 17 (GROUND)

Thermal effect: 77 hours at 62 degrees

Thermal effect: 77 hours at 62 degrees

• First test on final setup of the soldering machine are positiveand confirm validity of technical choices

• Panels are (slowly) continuing the quality tests: no problemfound up to now; in the meantime the production has reached a good quality (at least for small ones)

• A “mini” production of chambers has taken place, where procedures and quality tests have been “trained”.

We can afford now with more confidence the construction of larger chambers

Conclusions

Documents

Status Report of activities in LNF Soldering procedure 1.Status of soldering machine 2.Measurement of wire position Chamber prototypes 1.Construction of