1 lead/emulsion compatibility in opera bricks short description of cngs and opera projects what is...

1

Lead/Emulsion compatibility in OPERA bricks

• Short description of CNGS and OPERA projects

• What is an OPERA “brick”

• Alternative packaging

• Technical description of OPERA Emulsions

• Emulsion/lead compatibility: tests @ CERN

• Emulsion/lead compatibility: tests @ Nagoya (Japan)

S. BuontempoINFN- Naples

2

The CNGS project

3

The OPERA Detector

SM1SM2

31 walls (brick walls+TT)

+ 1 spectrometer

spectrometer

31 Walls (each containing 3328 bricks)

In total there are 206336 bricks ~ 1.8 kton

4

The (light and strong) support structure for the “brick walls"

Tests of full scale prototypes (Frascati and Naples)

wall

Tensioning from the bottom

Suspension from the top

Brick loading test

Height ~ 6.7 m

1 full wall contains 64x52 = 3328 bricks = ~28.5 kton

5

Brick Manipulator System (BMS)

• Portico study completed (total weight 5 t )• full height test @ LAPP in 2004

Brick Manipulator Systemprototype used for extensive tests• programming and upgrade of the automation system• brick loading and safety protective skate

Brick loading system

6

What do we call a “brick” ?

ECC CSS CS(one emulsion sheet

covered by laminated paper)

Skates

Skates

Laminated paper

CartonpaperPile

(emulsion,lead,emulsion,…)

(exploded view, not to scale)

Baseline solution for packaging

7

Alternative brick packaging

8

BAM: Brick Assembly Machine

207000 bricks in one year = 1000 bricks/day = 2 bricks/min

Lead palletting

PilingRobot

Quality Check

CS + Skates gluing

ECC Packaging

Additional protection

Emulsion palletting

9

Technical description of OPERA emulsion films

When a charged particle goes trough emulsionthere is an energy loss , - dE/dx k Z2FThis energy excites AgBr grains along the trajectoryrealising the so called latent image.During developing and fixing baths excited grains arereduced to silver grains and they look like dark spots.

Avg. 30 grains/100 m

Plastic base

Protective gel layer 1m

Insensible gel layer 1m

Gelatine ( C, O, N...)

AgBr (1g Ag / film)

42 m

200 m

42 m

So all metals able to reduce Silver (Al, Fe etc...) are dangerous !!

10

Here there are some samples from CHORUS experiment...

interaction

Low energy electron tracks

nuclear fragments (black tracks)

Fog : a random grain in this view

Animation (neutrino interaction and a decay)

11

Emulsion/lead compatibilitytest @CERN

We performed several test on this purpose and results are the following for vacuum packaging.Authomatic and manual measurements gave us the result that the fog density in the case of lead contact is 10 times bigger.

For packaging without vacuum, we did not found an effect so dramatic.

Reference emulsion (fog density < 3 grains/(10)3)

Emulsion in contact with lead for 57 days(vacuum packaging, 20°C); fog density 27 grains/(10)3.

Animation

12

Emulsion/lead compatibility test @CERN

Summary of Tests performed in July

• Pb-Ca laminated with usual oil and cut with Rapid D oil • First time in long term contact with emulsion (51 days)• Unfortunately bad quality emulsion (fog= 10)• Vacuum and mechanical packaging tested

Vacuum at 20°C fog increase factor 3Vacuum at 34°C very high fog (not measurable)

Mechanical at 20°C no effectMechanical at 34°C minor effect (20%increase)

13


Summary of Tests performed in September

• Pb-Ca laminated with usual oil and cut with Rapid D oil• CERN pure lead• Pb-Ca degassed • Pb-Ca painted• Medium term contact with emulsion (20 days)• Unfortunately bad quality emulsion (fog = 5-10)• Vacuum and mechanical packaging tested

Vacuum at 20°C minor effect for any leadVacuum at 30°C minor effect for any lead

Mechanical at 20°C minor effect for any leadMechanical at 30°C minor effect for any lead

14


Summary of Tests performed in October

• 1) Pb-Ca laminated and cut with usual lamination oil• 2) Pb-Ca laminated and cut with usual lamination oil, “US cleaned”• 3) Pb-Ca laminated with usual oil and cut with Rapid D oil• 4) Pb-Ca laminated with usual oil and cut with Rapid D oil, “US cleaned”• Long term contact with emulsion (40 days)• Unfortunately bad quality emulsion (fog = 7)• Vacuum and mechanical packaging tested

Vacuum at 20°C factor 4 increase of fog with any leadVacuum at 30°C factor 5 increase of fog with any lead

Mechanical at 20°C no effect for any leadMechanical at 30°C no effect for any lead

15

Emulsion/lead compatibility test @ Nagoya (Japan)

Lead Plate

Film

Film

Paper Results Sample 1-1 Sample 1-2 Sample 1-3 Ref1-1 7.2+-0.6 5.2+-0.5 3.5+-0.3 3.3+-0.3 7.4+-0.6 4.4+-0.4 3.3+-0.3 3.2+-0.3

Paper

(Result1) The fog density decreases with the increase of the buffer space.

Test1. Effect of buffer space in the package• Short term contact with emulsion (14 days)• High temperature 40oC• Good quality emulsion (fog = 3)• Only vacuum packaging

Test to understand if it is a gas effect

16


Lead Plate

Film

Film

Results Sample 2-1 Sample 2-2 Sample 2-3 4.9+-0.5 Film 3 5.0+-0.5 7.0+-0.5 6.2+-0.5 Film 2 6.1+-0.5 5.8+-0.5 8.2+-0.6 7.2+-0.6 4.8+-0.5 F ilm 1 7.8+-0.6 6.8+-0.5 4.6+-0.4

Film 3 F ilm 2 F ilm 1

Test2. Effect of film numbers in the package

(Result2) Fog density decreases with the increase of the number of films.

These results (Test1 and Test2) are consistent with the hypothesis that the state of the matter, which increases the fog density, is a kind of gas.Probably a gas of low molecular weight because, the increase of the buffer space diluted the effect.

17


Tests on the origin of the gas. Out gas from lead? Contact & non-contact test

Lead Plate

Film

Film Paper

Results Sample 1-2 Sample 3 Ref 1-1 5.2+-0.5 4.7+-0.4 3.3+-0.4 4.4+-0.4 3.8+-0.4 3.1+-0.4 5.1+-0.5 3.1+-0.4 3.2+-0.4 4.4+-0.4 3.6+-0.4 3.0+-0.4

Paper

(Result3) Fog increase was suppressed in the case of non-contact

It can be concluded that the main part of the gas comes from the direct contact between film and lead

18


Attempts to inert the lead.

Treatment by H2SO4 (0.2N)

Results No treat Only Wash H2SO4 H2SO4 (with Oil) (Oil Removed) (1) (2) 5.1+-0.5 5.0+-0.5 3.4+-0.4 3.8+-0.4 4.4+-0.4 3.7+-0.4 3.2+-0.4 3.7+-0.4 5.1+-0.5 4.3+-0.4 3.3+-0.4 3.7+-0.4 4.6+-0.4 4.3+-0.4 3.4+-0.4 3.6+-0.4

(Result4-1) The treatment with H2SO4 suppressed the effect.(Result4-2) The surface oil did not suppress the gas creation (comparing no treat and only wash samples).

19


Treatment by temperature and vacuum

Results:

Treatment (3)

Treatment (4)Vacuum 100oC

With Oil Oil removed With Oil Oil removed

FD 6.8+/-0.5 5.1+/-0.5 8.1+/-0.6 7.2+/-0.6

(3) Leave the lead in air at 100oC for 4 days.(4) Leave the lead in vacuum (~20Torr) at 100°C for 4 days.After the treatment, the lead plates were cooled in air and vacuum-packed with films. The packed samples were kept at 40°C for 1 week.

(Result4-3) Both treatment worsen the situation

20


Lead treatment by water.

We put the lead in de-mineralized water at room temperature for 4 days.By the immersion, a lot of white precipitate (powder like) was created and the

corrosion was continued until the end of immersion. After the treatment, the lead plates were dried in air for a half day and

vacuum-packed with films. The packed samples were kept at 40oC for 1 week.

Result: The observed fog density is 4.1+/- 0.4. No clear improvement but no extra degradation.

21


Why two years old Pb-Ca is safe?

The surface of this sample is covered by a kind of passive state

In order to check this hypothesis, the surface of the two years old Pb-Ca was removed mechanically and the contact test was repeated.

Result: Fog increase was observed. FD= 5.9 +/- 0.4 after 40oC 1week

The toxic lead (Pb-Ca) and two-years-old Pb-Ca were immersed in de-mineralized water in order to check the resistivity against the water corrosion.

Result: in the case of toxic lead, as described in water treatment case, a lot of white precipitate (powder like) was created and the corrosion was not stopped. On the other hand, completely no corrosion was observed in the case of two years old Pb-Ca.

We can conclude that the surface of the two-years-old Pb-Ca is covered by a kind of passive state

22


Why only Pb-Ca shows the effect ?

In Ca lead we have

Ca + 2H2O -> Ca(OH)2 + H2

In pure lead we have

Pb + H2O + 1/2O2 -> Pb(OH)2

Why vacuum treatment worsens the situation?

This can be explained as the existence of the inverse reaction of the water reaction of calcium on the surface (need further study).

Comment:

….maybe under vacuum we just extract more water from emulsion (??)

23

Conclusions in JapanFirst conclusions from Japan are: 1) The origin is gas.2) The gas is dominantly created by the direct contact between emulsion film and the lead. 3) We found a method to inert the toxic lead. The method is a surface treatment with H2SO4, which make a kind of passive state on the lead surface. The passive state probably prevents the reaction between emulsion film and lead.

After some further discussions their advice is:There are many questions raised, especially the mechanical stability of the passive state. It should resist the expansion stress caused by temperature variation. It should resist the treatment of the BAM etc. Who will or how to prove it is OK for 12M lead plates (?)Maybe better to go to pure lead….

24

Conclusions in EuropeWe do not see any effect (or in the measurement error bars) on the fog in the mechanical packaging we need solidarguments before rejecting that packaging solution

We fear anyway a long term chemical aggression of the lead on emulsion further study on Pb/Em compatibility (Pb cleaning? surface treatment?) to minimize the risk

The main difference in mechanical packaging is the air tightness need further study in H2 atmosphere (very poisoning)

All the materials used in mechanical packaging (adhesive tape, thin PE, springs, etc) must be studied in terms of degassing.

Humidity tightness and stability inside the packaging should be studied for both packaging solutions.

1 lead/emulsion compatibility in opera bricks short description of cngs and opera projects what is...

Documents