Preliminary studies for Muon shield modification to accommodate LCLS II Alev Ibrahimov December, 2010 BSY

The Muon shield in BSY area consists over 100 steel blocks with approximately 23” X 23” x 80” dimensions. They are also 11 blocks with approximately 40” X 40” X50” dimensions. Every block from the first type weights over 5 ton and over 10 ton for the second type. Beam runs through the Muon shield almost in the middle of this steel shield (under the square blocks in the picture). The shield is about 47 feet long, over 13 feet in width and about 10 feet high. BSY BSY Existing Muon Shield

BSY BSY Existing Muon Shield The beam runs through the shield inside 2- 3/8” dia. tube (one piece tube, no flanges inside the shield) with welded on both sides 4-1/2” Conflat flanges. They are also bellows from both sides to compensate any misalignments. The existing beam tube is aligned on the upstream side and misaligned on the downstream side about 12mm X 15mm. Initial plan was to align the existing line during the new line installation, but after meeting with Dieter and Richard, looks like this misalignment is not going to be a problem and the existing line will stay the way it is. The tube is placed in steel shield cavity with cross section 16” X 9”. The volume between the tube and cavity walls is filled with lead bricks in size 2” X 4” X 8”. There are approximately 1000 lead bricks around the existing beam line. Upstream side shown

They are been different plans to run the second line through the Muon shield, including drilling a hole into existing steel shield using outside company specialized in such operations or removing all blocks from the new line area and using new blocks with sizes and shapes allowing easy installation. The other option, looking reasonable is to remove and modify (by removing material from the existing blocks) only affected from the new beam line blocks. All blocks, need to be removed are shown in blue and green color. BSY BSY Muon Shield modification They are 23 altogether and 12 of them need to be modified by machining (shown in green). The first 7 blocks orientation is perpendicular to the beam direction. Shown is only right hand side of the existing shield (looking downstream) affected by the new beam line. The existing beam line is shown outside the shield in left.

The “U” shape slot needs to be machined to the perpendicular blocks to accommodate the new line and the rest of the 5 blocks (aligned with beam direction) need “L” shape machined slot (corner 10” X 14” will be removed). Better option is to align these 7 blocks with the beam direction. Then only 2 instead of 7 blocks (with “U” shape slots) will be modified or altogether 7 blocks will need their corner to be machined off. BSY BSY Muon Shield modification If all blocks are aligned to the beam direction, only 7 blocks (in green) will need machining. Shown is only right hand side of the existing shield (looking downstream) affected by the new beam line. The existing beam line is shown outside the shield.

There is an option Muon shield to be only 40 feet in length, because of the reduced beam energy. Then there will be only 6 steel blocks to be modified. Since the machined slot is 10” X 14” in cross section, approximately cubic inches need to be removed from every block. The total amount material need to be removed will be about cubic inches (almost 40 cubic feet). Existing horizontal mill, we have in heavy manufacturing department, has main motor with 40 hp. This will allow about 25 cubic inches of removal rate max. BSY BSY Muon Shield modification Only 6 blocks will be modified for LCLS II if they are aligned along the beam line. Shown is only right hand side of the existing shield (looking downstream) affected by the new beam line. The existing beam line is shown 25” X 25” off from the new line in left and down.

Then machining time for all six blocks will be around 6 days (8h shift each). Taking in account, tool replacing and set up time this will double. Also, this machine is with a “spray” type cooling, which will reduce down the removal rate. Then realistic time to machine these blocks will be between three and four weeks. All these calculations are for low carbon steel material. These blocks are built from “leftover’s” from a steel manufacturing company and their actual material properties will vary from block to block and inside every block. If they are blocks from high carbon steel or part of them is from this material, this will reduce the material removal rate significantly. If they are sections in this blocks with modified carbon structures (typical for iron), then the hardness in some spots will be so great that they can’t be machined with conventional tools. After all this said we should be prepared for at least a mouth machining time for these blocks. Big concern machining these blocks will be the fact that they been exposed to radiation for so long and their unknown material properties. BSY BSY Muon Shield modification

Another option for the Muon shield modification is to rearrange the right hand side of the shield where the new line will penetrate. Looking at the picture below we can see that the blocks, where the new beam line will go through, are elevated by three rows of lead breaks. Removing these lead bricks will allow to lower the blocks enough for the new beam line to go over their top surfaces. BSY BSY Muon Shield modification The approximate new beam line location is shown with a little red dot surrounded by four yellow dots. Removing the lead blocks will allow new beam line to run over the blocks top surfaces.

Summary After the meeting with Dieter and his experience with the outside drilling companies, the firs option, drilling on the site was dismissed. They are following options to be considered: –Removing seven blocks from BSY and sending them for machining in our heavy manufacturing facility; –Rearranging most of the blocks on the right side of the existing beam line in order to allow the new beam line tube to run over the blocks not through them. This will take every block around the new beam line to be measured (their cross section dimensions vary from 20” X 20” to 24” X 24”) and put in exact spot in the Muon Shield. –Removing 23 blocks from the existing shield (if the shield length stays as is), scraping seven blocks – the one’s penetrated by the new line. Filling the big cavity (23” X 23” X 47’) with custom made blocks or by laser or water jet cut sheet pieces combined with lead brigs.

Summary Covering the top row with the existing blocks (use all minus seven scraped; –Scraping seven blocks (where new line penetrates, and filling the cavity with custom casted concrete blocks. Shield length stays the same. From all options looks like the most economical approach will be to remove only blocks needed for the new line, use new material around the new line (concrete, steel, lead), scrap seven blocks and use the rest of the old blocks to restore the original shape of the shield. Below reused blocks are shown in blue. The new beam line is in green. Seven blocks where the new line is penetrating through are removed. The blocks in orange stay in place. The volume for these seven removed blocks will be filled with lead bricks or concrete or steel sheets or combination of those.

Summary