Magnetic shielding meeting: 2012-09-12: 15:00 BST

Conference Room 4, R1 (phone conference details circulated)

Present: JT, VF, JW, IM, TH, AN, KL, MC, CMacW, PS, ABr, MZ, PH, JC, LC

	1.	Actions:
	⁃	PS: Update geometry and add quads;
	⁃	Quads added this am -- see later.
	⁃	AN,KL: How to add effort (perhaps B.Sheppard);
	⁃	RP believed to have met J.Clarke.  Will find status of this for next week's meeting.
	⁃	PS, MC: Send transverse forces to mailing list;
	⁃	Stands.  MC has the data for Steps IV, V and VI.  Model takes a long time to run, but returns reasonable results.  Forces believe to be manageable except Step V in a particular mode.  Details will be circulated;
	⁃	JT: evaluate cost and complexity of shielding compressors at south wall
	⁃	JT has received information from Magnetic Shields.  Original quote of ~£25k reduced to ~£12k.  Done.  Needs to inform future considerations.
	⁃	MC: evaluate effect of racks on field in RF area;
	⁃	See below.
	⁃	TH, JT, IM, MC, AG, RP: Write paper for presentation to the TB for positioning of the racks behind north wall;
	⁃	Agreed:
	⁃	Finalise the report by 05Sep12;
	⁃	Review at our meeting on 05Sep12;
	⁃	Send AN for TB on 07Aug12.
	⁃	Done.
	⁃	IM: Check content and limit on operation of the substation;
	⁃	A. Gallagher reported that the manufacturer had reported that 0.5 G is the limit.  This indicates that they don't know.  Implies we need to study.  Done.
	⁃	PS, MC: Consult C. Rogers on version management scheme;
	⁃	PS has obtained and account on LanchPad; action stands.
	⁃	RP: check with SS team what the experience is;
	⁃	Action transferred to ABr.  ABr will try and generate information in short order.  MZ points out that the equipment is only ~6m away;
	⁃	JT: notes that up to 100 ft there is no drop in performance.  If two hoses are joined together there is a 2-3% drop in performance. Need to check if this is the same for single and two-stage units.  Need to re-tune compressors.  We don't know what the re-tuning means.  Need also to re-evaluate the effect of the 50Hz versus 60Hz mains;
	⁃	Agreed:
	⁃	Check basis of Cryomech estimation;
	⁃	Check Cryomech figures with FC (or SS) as soon as we can;
	⁃	Also need to do same for Sumitomo compressors and hoses.
	⁃	JT: Pursues Cryomech basis of estimation;
	⁃	CMacW: Liaises with Sumitomo;
	⁃	ABr: Will check double-lengths of Cryomech hoses;

	2.	Status of review of items in Hall and contacts with system owners:		LF/MOM
	⁃	IM has provided information to LF on DL responsibilities;
	⁃	Will try and get hold of some more information as MOM;

	3.	Status of magnetic model of MICE Hall								PS
	⁃	See slides:
	⁃	Need to include EMR and an approximation to the iron buried under the floor before we begin to discuss the model estimations of the fields on the west wall;
	⁃	MC: presented field maps and will distribute information to mailing list.  Points noted:
	⁃	Substation:
	⁃	Study of fine details of structures has been difficult.  But, MC has results for effect on racks behind the north wall and the sub-station.  Difficulty is in the cladding of the racks which is 3mm thick, but large in surface area.
	⁃	MC took VB's models which were used to assess the quantity of shielding that would be needed to shield a compressor.  This model was modified such that the cabinet frame was represented as the first layer of screening material.  Results indicate that the sub-station will see on its outer surface see maximum field of 550 G.  This is concentrated in the area between the two substation components.  Sub-station has many panel-mounted components so the effect of the field is worse than it might be.
	⁃	Inside, if it is assumed that the components are localised the field is at the level of 30 G.  
	⁃	JC notes that the transformer has a transformer; the field at the transformer seems to be ~30 G.
	⁃	This is initial information for working out what the options for mitigating the effect of the stray field on the substation;
	⁃	Racks behind the north wall:
	⁃	Seven racks and a blister were modelled behind the north wall.  Found that external surfaces of the racks will see 300-620 G.  Inside the racks you will see only 18G.  Still a large field.
	⁃	Need to review the distribution of the magnetic field in the iron and in the racks;
	⁃	208 V transformer in the trench:
	⁃	Case will see 0.24 T and field inside the transformer case will be at 81G;
	⁃	Transformer is positioned in line with the Virostek plate upstream of the spectrometer.  Q9 was not in the model;
	4.	Discussion of options:
	⁃	Racks: 
	⁃	Behind north magnetic shield wall: status report			TH
	⁃	ABr: raises issue of cables for spectrometer solenoids.  The cable management has been speced bearing this in mind.  Cable lengths will be an issue.  May need to make new cables;

	⁃	On the mezzanine level to the north east;
	⁃	Back-up scenario at the moment;

	⁃	Compressors:											TH, JT
	⁃	Along west wall;
	⁃	JT: working on routing of high-pressure hoses from the magnets and tracker cryostats to the west wall;

	⁃	ISIS plant room:											KL
	⁃	

	⁃	Partial return yokes:										HW
	⁃	No report from HW this week.  ABr reports that present work of HW has completed but can discuss how to take this forward at/after the TB.  ABr has tried to find additional engineering effort at FNAL.  
	⁃	JT: provide ABr with drawings to ABr for transmission to FNAL engineer;

	⁃	Igloo:
	⁃	Closure of ends of shield wall.
	⁃	On hold for the moment.
	
	5.	Exposure of equipment to magnetic field							CMacW, RP
	⁃	CMacW: first step is some data from the SS would be valuable.
	⁃	Long discussion of idea of making a worked example.  This did not lead to a good conclusion.  Issue seems to come down to defining specifications and then designing shielding to meet the specifications.
	⁃	Remove as agenda item; replace with progress on design of shielding for tracker cryostat and electronics;

	6.	List of specific items to check									PS
	⁃	LH2 delivery systems 
	⁃	Q9 power supply
	⁃	HV rack
	⁃	Control rack for compressors, vacuum etc.
	⁃	Vacuum pumps
	⁃	Substation
	⁃	Equipment on the roof

	6.	AoB
	⁃	PH: see slides.  Points noted:
	⁃	PH made the case that a 2D simulation might be useful to guide where to put the effort for the 3D model.
	⁃	Basic principle of 2D to guide intuition accepted.
	⁃	PH: presentation at MAP meeting in October.  Agreed that sharing slides in advance is a reasonable way forward.

Summary of actions:
	⁃	AN,KL: How to add effort (perhaps B.Sheppard);
	⁃	PS, MC: Send transverse forces to mailing list;
	⁃	PS, MC: Consult C. Rogers on version management scheme;
	⁃	ABr: check with SS team what the experience is;
	⁃	JT: Pursue clarification of Cryomech basis of estimation of effect of high-pressure hose length;
	⁃	CMacW: Pursue development of test of non-standard lengths of Sumitomo high-pressure hose;
	⁃	ABr: Pursue development of test of non-standard lengths of Cryomech hoses;