CCLRC Engineering and Instrumentation Department – Project Engineering Division – Mechanical Design Group

NOTE ADR026/WP185/023

ALVEOLAR ENVELOPE GAUGING

CMS-ECAL-EE Super Crystal – Alveolar Inspection 2ND February 2005

Alveolar Unit Envelope Size Gauging

ALVEOLAR - 0-TB-0054-103-00-D

SUPER CRYSTAL ENVELOPE - 1-TB-0054-118-00-C

Many of the Alveolar units measured at CERN are over the original specified limits. To avoid rejecting to many units the allowances were reviewed. It was agreed that the Alveolar size could be allowed to go up to the specified envelope size without causing any likely problems. However in some cases the Alveolar units exceeded these new limits. Agreement was reached that a small portion of the gap size may be used as long as it could be demonstrated that the Alveolar Unit remains within this enlarged envelope. To check that each Alveolar Unit is within the enlarged envelope, they are to be checked using one of the assembly jigs set up as a gauge. An Alveolar Unit of standard size is to be used to set up the jig, and from the protrusion amounts the actual envelope size can be determined.

Measurements and Cell Gauging:

See Alveolar Gauging Instruction Sheet ADR026/WP165/IS002

ALVEOLAR - 0-TB-0054-103-00-D

Standard Specification:

Front Rear

145.52mm 154.20mm

145.78mm 154.45mm

Corrected mandrel gauge protrusion: 16.09 – 29.52mm

Super Crystal Envelope maximum limits:

Front Rear

145.98 mm 154.65 mm

Enlarged Envelope:

Front Rear

146.08mm 154.75mm

ALVEOLAR ENVELOPE GAUGE

An Alveolar unit that had been previously measured at RAL was used to set up the jig.

Unit used to set jig – 3-18

Alveolar Unit – 0-TB-0054-103-00-D
Mandrel Gauge Protrusion – 18.90 to 22.46 mm
Date / Unit / Face / Front / Front / Rear / Rear
22/11/99 / 3-18 / C / 145.472 / 145.553 / 154.213 / 154.247
D / 145.632 / 145.764 / 154.267 / 154.324

Measurements of Datum Alveolar Unit used to set up jig, with 1mm protrusion as the base line.

Note that each Alveolar Unit is tapered across face ‘C’ and face ‘D’ - this is normal.

Now the Alveolar unit has a taper of 1.801620. Thus 1mm = 0.03146mm

For face ‘C’ the top plate is set to match the taper

For face ‘D’ the side plate is set to the largest size.

RESULTS

Once the jig had been set using the standard size Alveolar Unit. The unit was taken out and put back several times good repeatability was achieved. Measurements varied from 1.2 to 0.9mm.

One of the largest measured units was then inserted and the protrusion measured at 8.5mm, and for one of the smaller units a 5mm protrusion was measured.

Table of sizes for a given protrusion

Protrusion / Face / Front / Front / Rear / Rear / Remarks
-1 / C / 145.48 / 154.18 / Check Cell size
-1 / D / 145.72 / 154.25 / Check Cell size
0 / C / 145.51 / 154.21 / Standard Specification
0 / D / 145.72 / 154.28 / Standard Specification
1 / C / 145.47 / 145.55 / 154.21 / 154.25 / Standard Specification
1 / D / 145.63 / 145.76 / 154.27 / 154.32 / Standard Specification
2 / C / 145.58 / 154.28 / Standard Specification
2 / D / 145.79 / 154.35 / Standard Specification
3 / C / 145.61 / 154.31 / Acceptable – Envelope Limits
3 / D / 145.82 / 154.38 / Acceptable – Envelope Limits
4 / C / 145.64 / 154.34 / Acceptable – Envelope Limits
4 / D / 145.85 / 154.41 / Acceptable – Envelope Limits
5 / C / 145.67 / 154.37 / Acceptable – Envelope Limits
5 / D / 145.88 / 154.44 / Acceptable – Envelope Limits
6 / C / 145.70 / 154.40 / Acceptable – Envelope Limits
6 / D / 145.91 / 154.47 / Acceptable – Envelope Limits
7 / C / 145.73 / 154.43 / Acceptable – Envelope Limits
7 / D / 145.94 / 154.50 / Acceptable – Envelope Limits
8 / C / 145.77 / 154.47 / Acceptable – Envelope Limits
8 / D / 145.98 / 154.54 / Acceptable – Envelope Limits
9 / C / 145.80 / 154.50 / Highest Limits
9 / D / 146.01 / 154.57 / Highest Limits
10 / C / 145.83 / 154.53 / Highest Limits
10 / D / 146.04 / 154.60 / Highest Limits
11 / C / 145.86 / 154.56 / Maximum limit - Measure
11 / D / 146.07 / 154.53 / Maximum limit - Measure

CONCLUSION

Good correlation between measured Alveolar size and gauged protrusion was obtained, making this a suitable method for checking envelope size. This method does not check Cell size.

The above table gives the ranges, below 0 the cell size will need to be checked for suitability. Between 0 and 2 indicated Alveolar Unit within standard specification. Between 3 and 8 Alveolar units are within the maximum super crystal envelope size and will be acceptable. Between 9 and 10 the Alveolar Units are usable at certain selected positions. At 11 the Alveolar unit is at the maximum limit and is to be carefully measured to determine if a suitable position can be found.

B Smith

03/02/05