Dear Xiaochao, >Have you had time to look into the questions we sent on Feb. 7th (attached below)? The engineers from >Argonne National Lab are waiting for this information to continue their design on the support structure, and I >will really appreciate your answers on a timely manner. > >In addition, would you provide information on the material of the steel rods that penetrate the modules? >What exact type of material will be used? Because these modules will be placed inside strong magnetic >fields, no magnetic material can be used. Even for stainless steel, for which different types have different >degrees of magnetism, some of them will not meet our requirement. Therefore if you have experience in >which type of stainless steel was used previously, with known (non-)magnetism, we will appreciate such >information as well. We used a rods produced from usual steel, it's a steel CT.3 (Russian name). But I built a few modules with rods from stainless nonmagnetic steel (12X18M10T Russian name). I don't see any problems to use stainless steel rods for Shashlyk modules. I used steel rods due to the same radiation length of steel and our sampling structure of module. In your case may be better will used a bronze rod with smaller radiation lenght. >Thanks for your last email dated Jan. 17th. For the new Preshower design (two scintillator planes >sandwiching a lead layer), we are still trying to complete the simulation that determines the plane size, shape, >PID performance, etc. And so far we do not have a detailed design drawing yet. > >But let's take this opportunity to focus on the support structure of the Shower modules. The engineers at >Argonne National Lab are working on designing the support structure and currently we have a few questions: > >1) What are the fabrication tolerances for the modules? In other words, how much room should the >supporting structure >leave between the modules? The transverse size of our Shashlyk module is 38.15x38.15mm**2, it's average value. The spreads of transverse size is 0.04mm. We are measured a few hundred modules. We are installed a steel tapes 0.1mm thickness inside calorimeter cassette (see photo) with step 38.3mm. The main goals of the installation the tapes was fixed a modules step and made sure verticality of modules. Also we put on top of each modules a steel tape with 0.1mm thickness. Two reason for this: 1) to keep the same step as in gorizontal; 2) distribution of loading on whole module. Few words about sources of the variation on module size: 1) variation of individual plate of scintillator and lead, it's value no more than 0.01mm; 2) variation position of individual plates with respect to steel rods. The diameter of hole for support rod in scintillator and lead is 1.5mm, but diameter of rod is 1.4mm. The difference between diameter of hole and rod can be reduced on two times. >2) The engineers are considering supporting all shower modules by the steel rods that penetrate these >modules. Therefore, what is the tension in the rods that are used to hold the blocks together? What are the >rod diameters? This >question is getting at how rigid the modules are physically and what we can count on if we are just supporting >at either one and/or both ends. We don't measured the tension in the rods, sorry. I can describe the main steps of assembling of the our Shashlyk modules: 1) 4 steel rods are fixed on front flange; 2) all scintillators and lead plates put on this rods; 3) second flange also put on this rod; 4) whole plates compress until fixed length. The fixed length and amount of pair scintillator and lead plates we are identified by experiment. >3) In reading some of the modules made by IHEP, it was noticed that the KOPIO design has some "LEGO" >bits. Are these still relevant for the COMPASS or our SoLID EC design? > >What is the purpose of these "Lego" bits in the KOPIO Design (see Fig.1 in B.S. Atoian /et al/ NIM 584, >http://www.sciencedirect.com/science/article/pii/S0168900207021717" >The concern is that one must be careful to have either all the tension on the Lego bits or none of it there. I known that in last KOPIO modules also used a steel rods for support. LEGO fixing is very elegant, but module isn't rigid and LEGO bits source of non uniformity. >4) We are strongly considering a hexagonal shape, since the stacking in pseudo-wedges might be easier. Are >there any problems with this? I don't see significant additional problem with production and assemble modules of hexagonal shape. > My understanding is that there will be 6 extra month of fabrication time and extra time >for testing the modules, is that correct? What will be the main properties to be addressed by such tests? Yes, 6 month will be need for production of molds for scintillator and lead. Main goal of this test is check every step of production and assembling. In result we will have all information about properties of modules: energy and space resolution, uniformity, rigidness, spreads size of module and other. Also your team collect a expirience a working with future calorimeter modules and check MC simulation. Best regards, Vladimir.