Mechanics and Cooling Systems for the CBM STS

Mechanics and Cooling Systems for the CBM STS CONTENT 1. Initial parameters for design - The scheme of stations - The beam pipe - The variants of detectors plates for ladders STS - The scheme of area of detecting - Variants of schemes of detector's positions for station 4 2. Structure of station 4 3. Structure of centre ladder for station 4 - Carbon fiber frame calculation and optimization - Schell for central frame only - Mechanical assembly of detectors - Ladders support system - Detector’s plates holder - Plate of final electronics 4. Conclusion SAINT-PETERSBURG STATE UNIVERSITY S. Igolkin , e-mail Igolkin @hiex. phys. spbu. ru Serguei. Igolkine@cern. ch Karelia , Russia , 01 June 2009

The scheme of station See report J. Heuser (Protvino June 2008)

Beam pipe, Option See report S. Belogurov (Protvino June 2008) The alternative to Be is CF reinforced plastic. It is supposed to have the first feed back from the IVW (Institute for composite material research Kaiserslautern, Germany) The main points for the comparison: min. feasible thickness and price (0. 5 -0. 7 mm and ~100 -150 k Euro for Be)

The variants of detectors plates for ladders STS The sizes of base plates of detectors were offered by J. Heuser

The scheme of area of detecting 1. 2. 3. 4. 5. Distances between stations are accepted equal - 100 mm The detecting zone in a vertical plane is limited by a solid angle - 25 deg The detecting zone in a horizontal plane is limited by a solid angle - 27 deg External diameter of a beam pipe at the first station is accepted - 41 mm External diameter of a beam pipe at the eighth station - 56 mm

Variants of schemes of detector's positions for station 4 For all option: The maximum quantity of detector plates on a ladder -10 pc (on each side -5 pc) Option 1. The central zone round a beam pipe has an open area a constant for all station STS - 60 x 60 mm Positive factor : The big repeatability of positioning of detectors and therefore decrease in quantity of assembly equipment and quantity of different length of cables. Negative factor: presence of additional open area round a beam pipe for station 3…. 7 Option 2. The central zone round a beam pipe has an closed area for all station STS Negative factor: - additional overlapping of active zones various for each station - big quantity of assembly equipment and quantity of different length of cables. Option 3. The central zone round a beam pipe has an closed area for all station STS Positive factor: Advantage of the offered scheme of placing of detectors in relation to a option 2 - decrease in quantity of assembly equipment and quantity of different length of cables. Negative factor: - additional overlapping of active zones in vertical plane various for each station

Structure of station 4 1. Each station consists of four frameworks with r ladders of detectors: two forward and two back, 2. Frameworks in pairs, forward/back are positioned and fixed on frameworks of linear bearings with a pin system. 3. Accuracy of moving of the carriage of the linear bearing-6 mcm

STS lateral view ( station from 4 till 8) 1. Positioning of ladders on frameworks is carried out through prisms leaning on ruby spherical support

Structure of centre ladder for station 4 The ladder consists from: 1. Carbon fiber frame with L-leg and centre shell. 2. End blocks P-type and V –type 3. Cooling blocks 4. Detectors plates with analog cables hybrids.

Carbon fiber frame Material: CF prepreg M 55 J/ 334 EU Modulus of composite 32800 Gpa

ANSYS Calculation by Dr. Dobulevich V. M. • • Rigidity of the frame was defined in two directions: perpendicular to the plane which is passing through the bottom beams in a direction of axis Z, (fig. 1), and along the plane which is passing through the bottom beams in a direction of axis Y, ( fig. 2). Also it was characterised by its deflection (Uz - on axis Z and Uy on axis Y) under the influence of total force 100 g. Boundary conditions: swivel joint in sites on distance of 40 mm from the frame ends.

Relations: Proportion of frame’s elements, mass property and deflections

Table 1 Relations: Proportion of frame’s elements, mass property and deflections Options Bu (mm) Bd (mm) M (g) Uz (mcm) Uy (mcm) 1 (main) 2 2, 5 7, 92 24, 6 11, 5 2 1, 7 2, 2 7, 43 26, 8 12, 3 3 1, 7 2, 086 7, 23 27, 4 12, 8 4 2, 25 2, 5 8, 14 22, 4 11, 5 5 2, 5 8, 37 20, 7 11, 4 6 2, 25 7, 43 25, 5 12, 6 7 2 2 6, 96 26, 6 14 8 2 2 7, 18 24, 4 14 9 1, 7 6, 89 24, 9 15, 5 10 R of ribs 0, 4 mm 2 2 6, 89 24, 4 16 Conclusions The carried out settlement researches of influence of the sizes of elements of a ruler on its rigidity and weight have shown: 1. Effective decrease in weight of a ruler with preservation of its rigidity occurs at reduction of length of shelves of the bottom beams to the reasonable minimum caused by technological restrictions, to simultaneous compensating increase in length of shelves of the top beam; 2. Reduction of radius of rib's cross-section of longitudinal and diagonal edges to 0, 4 mm reduces weight of a frame, and saving its rigidity for any options.

Shell element - only for centre frame 1. The detail consists of an internal part made of foam plastic AIREX and carbon fiber covers in the thickness 0, 15 mm. Masse of Shell = 1, 4 g 2. CF properties : specific density 1, 92 g/cm 3 Xo = 25 cm 3. AIREX properties specific density 0, 05 g/cm 3 Xo = 1380 cm

The central part of a central frame For a possibility of placing of a beam pipe between left and half of station, two central frames have an original design. The centre part of a frame has break, sufficient for beam pipe placing, and for supply of rigidity of a broken frame has used "Shell" element Such design has used for all central frames at all eight stations. Shell element – it’s universal for all central frames. Now Dr. Dobulevich has to do the calculation on ANSYS for optimization of the sizes of a shell.

Mechanical assembly of detectors Fig. 1 Fig. 3 Fig. 2 1. The lateral plane of detector plates is used for detector positioning on the assembly adaptation. 2. The inside is completely closed by an analogue cable. 3. Hereby, for fixing of plates on a frame - lateral faces are used. For improvement of adaptability to manufacture of connection of detectors with L-legs it’s can used ceramic spacers (see Fig 1) 4. The ceramics with the detector is glued on chemically neutral glue. (see Fig 3) Masse of one = 0, 0042 g 5. For assembly of the module of detectors plates in addition used the CF plates (see Fig 2) The Thickness = 0, 3 mm ; Width = 2. 2 mm and length 175 mm Weight of one plate 0. 25 g

Ladders support system Fig. 1 Fig. 2 Each end of ladder has a final support. (See Fig. 1) Final support consists of: a plate with precise basis elements (surfaces) and two prism’s: V-type (See Fig. 2) and P-type (See Fig. 3 ) Assembly of end support’s and frame perform on the assembly jig at the same time with detectors holders Llegs. The hight precision of assembly jig ensures precise disposition of the all elements of the ladder. The critical part providing precision positioning of ladder is a ruby support (See Fig. 4) Fig. 4 Fig. 3

Detector’s plates holder Fig. 1 Fig. 2 1. The typical detail L-leg - is presented in Fig. 1. Section of a detail 0. 45 х 2 mm The detail can be made of glass fiber or carbon fiber. The weight of the detail varies from 0. 013 g to 0. 03 g depending on the sizes 2. For assembly of L-legs with a frame: - L - legs precision positioning on the assembly jig. - Epoxy glue is deposited on contact surfaces. - The frame is basing on landing surfaces and prisms - The curing process is done In such position Fig. 2 3. In future L- legs are used for fastening to them of detector plates Fig. 3

Cooling block for hybrids Fig. 1 Fig. 2 1. The box for the plates of final electronics consists of two lateral walls with directing grooves for fixation of electronics plates and two fastening walls. On external planes of lateral walls grooves in which are made tubes cooling system are pasted. Electronics plates are drawn in by flat springs to walls of directing grooves. The top and bottom parts of a box can be closed by thermo insulators walls. In this case the box will Fig be not radiate heat in surrounding space. 2. The box are fastened to the basic block of a ladder by screws. The electronic plates are located under a corner to a vertical plane that allows their statement and dismantle without a stretch and sagging of cables. See Fig. 2 Weight of one block with the complete set of electronic plates 110 г

Plate of final electronics On the given page the variant of placing of chips of final electronics on a plate is offered. The cooling block is developed for such variant presented on previous page. On a Fig. 2 and Fig. 3 The variants of a design of system of heat removal from electronics chips. Such variant has been realised in the ALICE project are presented. Distinctive feature of this variant is the minimum mass of cooling system. All parts are made from CF with heat conductivity factor nearby 500 The choice of a final design depends on many factors and in particular from specification of requirements of the physical program of experiment.

Conclusions. 1. The scheme of placing of detecting stations is offered with parameters: - distance between stations -100 mm - the detecting zone in a vertical plane - 25 deg - the detecting zone in a horizontal plane -27 deg - external diameter of a beam pipe for first station -41 mm - external diameter of a beam pipe for the eight station -56 mm 2. The variants of placing of detectors for station 4 are offered ( with different tilling) Earlier variants of placing of detectors for all eight stations have been drawn and dispatched interested persons 3. The universal design of the central CF Frame ensuring of assembly is offered. (of station with central beam pipe and possibility of easy replacement of ladders). 4. The calculations of sagging of CF frame under the central loading 100 g are made The elements of the frame are optimized (result - see page 13) 5. The limiting size for a central ladder for station 8 Is defined. The gap for the Dipole magnet ( according to main frame - 1410 mm) to be discussed. 6. The cooling block for final electronics is developed. The size of block 78 x 70 x 30 mm Weight 110 g For placement 10 electronic plates 7. The variant of placing of chips on a payment of final electronics is offered. The size of plate 70 x 30 mm ( 8 chips CBM XYTER) 8. The design of frameworks of station with ladder with use of the precision linear bearing for the moving is offered. Accuracy of moving in limits 500 мм - 6 мкм

The main current task To produce industrial equipment for production of CF frame and elements Now the mechanics of the vacuum back for production of composite feedstock of ladders: plates of modules, L- legs, thermal bridges is ready. Manufacturing electrical heaters and contact substrates mounting and adjustment is needed. Drawings of mold for manufacture of frame are made. Now it is necessary to find money for the manufacturing. Meanwhile it is possible to use for manufacture of experimental frame of the mold of the project ALICE. The length of matrixes allows to make frames in length up to 700 mm.