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2009 Summer Updates- Summer Student ReportEmine AltuntasStephen Fee

Supervisors: Mar Capeans, Ivan Glushkov, Roberto Guida

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Gamma Irradiation

Facility (GIF) RPC

Gas System

+GIF Humidity and Temperature Control System – The Tent

Construction and operation of the tent

Purpose of tent:

- Controlled environment for temperature and humidity for the chambers

- Achieved by temperature and humidity control devices

- Conditions monitored by measurement devices in the tent

- Tent is now sealed and operational at the GIF!

Current Status Inside The GIF

2 m 2 m

2.5

m

+GIF Humidity and Temperature Control System – The Tent

Current Status Inside The Tent

+GIF Irradiation positioning

RPC Tent

ATLAS TentOld

position

Safety zone

Safe

ty zo

ne

ATLAS Tent

Desired position

+ GIF Humidity and Temperature Control System – The Tent

- Current conditions in tent are approximately 40 %RH to 50 %RH, temperature of 20 °C

- Maintained at this state by the dehumidifier and air conditioning

Air conditioner - Control of Temperature and Dehumidification (but not to setpoint)-Dehumidifier - Dehumidification (not to setpoint)-Both are protected by lead shielding

- Limitations: the devices cannot be controlled remotely, no set point for humidity

+GIF Humidity and Temperature Control System – The Tent

Measurement Devices in Tent

Hygrometer

Weather Station

- Hygrometer gives measurement of temperature and humidity in the tent

- No need to protect from radiation – mechanical device

- Needs regular checks for ink and paper changing-Weather station records live data to a PC in the GIF

- This data can be accessed remotely at any timeConclusion: We now have a system to control and measure the temperature and humidity for the chambers

+Checklist for the GIF - RPC Gas System

The RPC gas system checklist is completed every day.

A hard copy of each day’s checklist as well as an excel file record is kept for future data analysis.

In addition to the points shown here the supply mixture peak areas and the MS vacuum quality concentration units are recorded.

The supply mixture peak area and concentration values can be found at https://twiki.cern.ch/twiki/bin/view/LHCgas/GCMS.

With the transition to the closed loop configuration new check points need to be added.

A log file is added to each day’s GC-MS analysis folder at the GIF.

Thus data collection process can be followed more accurately in the future.

Closed loop

Open mode

+Checklist for the GIF - RPC Gas System Right now the gas mixture is

analyzed with the MS-GC every day at 6 different points:

Supply gas mixture to the open loop Return gas mixture from the open

loop After MS5A purifier in the closed

loop After NiAl purifier in the closed loop After R11 in the closed loop The return mixture after all the

purifiers in the closed loop

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- Originally in the gas system, flow in ≠ flow out. More than 50% of gas was missing

- Does not represent closed loop conditions, and costs money

- Leaks suspected in the system

GIF Gas System - Leak Hunt

+Leak detection

- Firstly general gas detector and a Freon gas detector were used on the whole system

- These devices identified many leaks in the system

- Connection points, Teflon tape

- Solution: Tightening of connections, replace tape, assistance from technicians

- Still many leaks remained…

GIF Gas System - Leak Hunt

+Helium Leak Detector

Procedure:

-Run the system with 5% Hydrogen in nitrogen

- Hydrogen will be released at high rate through the smallest leaks (small molecular size)

- The detector was found to be very specific and accurate in the leak detection

- Leaks were then fixed, the system is now running with no major leaks

Conclusion: The helium leak detector is much more specific and faster than other methods and should be used for future leak detection

GIF Gas System - Leak Hunt

+Purifiers and Regeneration The Purifiers Tested At the GIF

The open loop purifiers

Molecular Sieve 3A, 4A, 5A

NiAl, NiSi, R11, R12, SiGel

2 l cartridges

The closed loop purifiers

Cartridge 1 (big one): 90 % MS4A + 10% MS5A

Cartridge 2 (small one): R11

Cartridge 3 (small one): NiAl 

The concentration levels of H2O and O2 are analyzed in every data collection.

Over time the sieves of each purifier become clogged. And purifiers do not perform at the desired level.

The increase in the tendencies of H2O and O2 levels indicate the need for regeneration.

+Purifiers and Regeneration Regeneration Process

The heat controller

Gas System Rack

Regenerator

Gas flow control rack

+Purifiers and Regeneration Regeneration Process

Inside the toaster the purifiers have been heated to 230 C

Each purifier is flushed with a standardized mixture of argon and 5% hydrogen.

In the case of MS4A and MS5A, as the purifier is heated the opening of the sieves increase.

As the purifier is flushed with gas, the molecules stuck between the sieves are removed.

Each purifier is regenerated for fourteen hours.

After the heat is turned down each purifier is flushed with the standardized gas mixture for another four hours.

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+Purifiers Table

4A 5A R11 Nickel Aluminium

Nominal Absoprtion capacity21% w/w

water22 % w/w

water 45-97 g/kg water No data

0% oxygen 0% oxygen4l O2 per 1 kg

catalyst17l O2 per 1l

catalyst

Amount in GIF set-up (g) 240.3 224.58 251.9 274.6

Expected lifetime for nomimal gas flow in GIF set-up (h)

Conditioning time (measured for each cartridge individually) [min]

Component of the RPC nominal gas mixture abosorbed by the purifier

Conditioning time of the whole set of absorbers together [min]

+GIF - RPC Gas System Checklist Data Analysis Purpose – To acquire

comprehensive and comparative graphs of the recorded values over time for further analysis

Method: The ISR RPC gas system checklist code is taken as the start point.

With the updates the current code;

Reads data records from the checklist excel file

The output graph files are recorded in the analysis folder

Each data entry is assigned to representative holder

Min and max finding for constructing the graphs

+GIF - RPC Gas System Checklist Data Analysis With the updates the current

code; A comparative graph of

active zone & open loop mixture temperature and RH values

A graph displaying the change in the current over time in each channel

The percentage deviation from the average current in each channel

Fresh gas mixture composition

+Air Calibration Report

Air calibration required to assist on ongoing gas measurements at the GIF

Aim: To achieve calibration for main components of air, plus additional components detected

Procedure: Analyse a known concentration of component using the GC-MS device

Result: The peak area can then be equated to the known concentration

+Air Calibration ReportOxygen Calibration

Achieved by analysing atmospheric air (21 %v/v oxygen) and bottle of 50 ppm oxygen in argon

Oxygen presents in module C (molecular sieve) of the GC (cannot separate air in modules A or B)

Oxygen could not be isolated from the 50 ppm analysis: Argon and oxygen peaks present at the same time

The calibration is thus based on analysis of air only

+Air Calibration Report

Achieved by analysing atmospheric air, 78 %v/v Nitrogen

Nitrogen presents in module C (molecular sieve) of the GC (cannot separate air in modules A or B)

Achieved by analysing atmospheric air

CO2 presents in module B (PPU) of the GC

The concentration of CO2 in atmospheric air is taken to be 0.0383 % v/v for the calibration calculations.

Nitrogen Calibration

Carbon Dioxide Calibration

+Air Calibration ReportWater Calibration

Achieved by analysing atmospheric air and bottle of 110 ppm water in argon

Water presents in module B (PPU) of the GC

Water peak from air Water peak from 110 ppm analysis

Ratio of peak area to concentration for 110 ppm analysis = 10.07

The two results are not in agreement. Reason : The air analysis is not guaranteed to be accurate due to the possibility of change in the absolute humidity of the sample. This is because of the discrepancy between atmospheric pressure and GC carrier gas pressure. Thus the calibration is based on 110ppm water in argon analysis

Ratio of peak area to concentration for air analysis = 1.35

+Air Calibration ReportArgon Calibration

Achieved by analysing bottle of (almost 100%) argon

Argon presents in modules A & B of the GC

+Air Calibration ReportConclusions

Calibration now available for the components of air:

Component Module Appearing in Time of peak value (s) Peak area corresponding to 1% v/v (µVs)

O2 MS5A 40 30987

N2 MS5A 43.6 30712

CO2 PPlotU 23.3 46823

H2O PPlotU 80.9 13541/100673

Ar OV1/PPlotU 17.3 14187/30644

+Looking Ahead The existing checklist needs to

updated with the addition of closed loop parameter readings

Such as, the closed loop temperature and humidity values

It is necessary to complete and test the ROOT checklist analysis code

For purifiers, regeneration is essential to be conducted without stopping the system and interrupting the data collection

Thus a similar setup to the one existing at LHC may be considered – of course taking into account time scale of this update and costs

The F- production rate to be studied

Hanna double channel analysis station

MS-GC software problems

The temperature and humidity control to be established for a long time in the tent –

no short term fluctuations

recording of values

+Acknowledgements

Experience with C++ and ROOT Introduction to the gas systems The physics behind the RPC’s

and RPC performance issues Other elements on RPC selection MS – GC analysis procedure Experience with MS – GC

software integration techniques Lectures by leading physicists in

the field Trips to the LHC experiments

Thanks for all the support And assistance And discussions -

explanations And fun conversations

+Personal Thoughts… The aims are challenging since:- Many impurities- Varying concentrations- Some concentrations very low = difficult to remove- Unknown effects on the chambers

Good Luck!

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+Acknowledgements and Thanks New experiences:- CERN- RPC- Working with radiation- Analysis methods and data analysis Outcomes:- Experience in international working environment- Further knowledge and experience in important areas- Looks great on my C.V.!

Thanks and please continue!

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