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[lcdds 260] modified assembly scheme for GLD

Subject:   [lcdds 260] modified assembly scheme for GLD
From:   "Seryi, Andrei" <seryi@xxxxxxxxxxxxxxxxx>
Date:   Wed, 6 Sep 2006 17:29:20 -0700

 
 Dear Sugimoto san and all, 

Could you please discuss if a modified scheme of 
GLD assembly, as shown in the file 
"questions_on_GLD_assembly.pdf", may be possible. 

In this case, it is assumed that central part of the
detector can rotate before installation of the solenoid. 
It looks that the width of the collider hall may be
reduced from 30m to 22m, giving significant savings 
in cost of hall, cranes, simplify support of beamlines, 
and reduce the need for beamline shielding. 

For comparison, the original GLD assembly scheme is also
attached ("exphall060821.pdf"). 

Also, the earlier questions of details of assembly, 
crane and shaft requirements (listed in the message below), 
still need to be discussed. 

 Best regards
  Andrei






-----Original Message-----
From: Seryi, Andrei [mailto:seryi@xxxxxxxxxxxxxxxxx] 
Sent: Thursday, August 31, 2006 9:56 PM
To: lcdds@xxxxxxxxxxxxxx
Cc: Martin Gastal; Jean-Luc Baldy; Vic Kuchler
Subject: [lcdds 255] Re: Minutes of 2nd Detector-assembly meeting


 Dear Sugimoto san and all, 

Optimization of 15m to 16-17m shaft, to accommodate 
the elevator is probably possible.

The crane vehicle as shown in CMS movie is probably
not the only possibility. We will ask CFS colleagues 
about this. 

For the wall in the hall, I am not sure if it can help
to make magnetic shielding. We were thinking to use just 
concrete wall, without much iron. 
What are the reasons to require magnetic shielding between
detectors? 

I believe we need more analysis of cranes, hall size and
details of assembly.  

Am I right that if you assume pure CMS style assembly, then
for GLD one would need 
   ~20m shaft
   2000t rented gantry crane on surface
   ~20t movable crane on surface
   ~20t crane in the hall

And with modified CMS assembly, one would need
   ~15m shaft
   ~400t movable crane on surface
   ~400t movable crane in the hall

I think we need to compare the cost and schedule in details. 
In particular, we need to take into account that:
  - most of procedure underground take longer than on surface
  - hall size requirements (especially height) may be 
   larger for 400t crane vs 20t

We requested the GDE management to create a mechanism to provide
parts of the CFS costs for such optimization. Hope this will happen, 
but if not, we have to do it anyway. 

For the hall width -- if the center part of the detector
can be rotated 90deg before insertion of solenoid, can 
it reduce the required width? 

 Best regards
  Andrei



-----Original Message-----
From: Yasuhiro Sugimoto [mailto:yasuhiro.sugimoto@xxxxxx] 
Sent: Tuesday, August 29, 2006 6:54 PM
To: lcdds@xxxxxxxxxxxxxx
Subject: [lcdds 252] Minutes of 2nd Detector-assembly meeting


GLD detector assembly task-force meeting minutes

   date:29 Aug. 2006
   attendants: A.Miyamoto, T.Omori, Y.Sugimoto, T.Tauchi, H.Yamaoka

1. Discussion on Andrei's  questions
   1-1.
>  Is it possible to equip the 15m collider hall shaft
>with elevator and stairs for personnel access as well?
>(motivation: removing the 9m access shaft near IP and
>relocating them to BSY)

      It seems too tight to share the 15m shaft with elevator
and stairs.  A larger diameter shaft (16 -- 17m) with elevator
and stairs is preferable.
     In order to construct the overhead crane (and others)
in the cavern,  a tall  crane vehicle has to be lowered beforehand.
We have to care  about the length of the crane vehicle when
we decide the shaft diameter.

   1-2.
>  Is the following suggestion acceptable:
>Include into the BDS cost only the cost of minimum size
>collider hall and small shaft.
>(for example 100L*20W*30H m^3 hall, two 9m shafts, no wall)
>The cost difference from the minimal configuration is
>included into detector cost.
>(E.g. delta cost of increasing the shafts to 15m and
>increasing the hall size, and adding the shielding wall)
>  Motivation: more clear comparison of detectors and
>streamlining the overall optimization.

      This issue has already been discussed in the lcdds mailing list.
We confirmed that we should assume the size of the experimental hall
and the diameter of the shaft as we (GLD)  think necessary.

      We think we may need the wall between two experimental halls  for
radiation safety reason.   The radiation control  area is classified
into several levels. At KEK, for example, the classification is
as follows (I don't know the proper English words, though);
Off-limits area  (No one can enter) :  > 10 rem/h
Restricted area (Special permission required) : > 2 mrem/h
General controlled area (Need qualification and ID card) : > 150 micro-rem/h
bra-bra-bra-
      If only the researchers work in the hall  when beam is on,  then
the radiation level of  less than 10 rem/h would be OK and no wall
would be necessary. However, when one detector gets wrong and
the maintenance work by company people is necessary, the area
should be the "General controlled area", i.e., the radiation level
should be less than 2 mrem/h. To achieve this level with the other
detector running,  we may need the wall between the two experimental
areas.
      The wall could  work as a magnetic shield as well as radiation shield.
If one detector  makes a strong leakage field, the wall  might be
necessary.
      The wall may not have to be as high as the experimental hall itself.
Anyway, we need more simulation work to get conclusion.

   1-3.
>In the Vancouver configuration there was an additional
>service cavern (where detector equipment can be placed).
>It may be the case that the hadron machines with their
>higher event rate and fast triggers do need such cavern.
>Can we remove this cavern and put all the detector equipment
>and services in the experimental hall?

      We could not find any reason to refuse the removal of the
service cavern from the viewpoint of detector construction.
However,  we are anxious about the removal of 9m shaft.
If  accelerator components are lowered using the shaft in the
experimental hall,  it could cause the conflict  with detector
assembly.


2. Discussion on crane capability

     We discussed about the construction procedure of
the iron structure.  However, it is not clear yet whether
we can construct it satisfactorily without 400t crane
in the experimental hall. So we would like to stick to the
400t crane option.
      A Japanese company (IUK) can provide us with 400t crane
"off the shelf".

-------------------------------------------------------------------------------

Yasuhiro Sugimoto
KEK


Attachment: exphall060821.pdf
Description: exphall060821.pdf

Attachment: questions_on_GLD_assembly.pdf
Description: questions_on_GLD_assembly.pdf