KLM at Belle-II

P. Pakhlov(ITEP)

Test of long strips(R. Mizuk, I. Tikhomirov)

For TDR we used short strips (no long strips were available) and extrapolated light yields using measured attenuation in the Y11 fiber.

Improve groove preparation: Vladimir: saw rounded groove Fermilab: found encrustation on the groove wall brush groove mechanically difficult to avoid air

bubbles in the optical gel around corners!

Cosmics test setup

4 stripstriggers

25cm2.8m

SiPMreadout

testedsimultaneously

mirrors

Longitudinal profile of light yield

Light yield is slightly better than reported in TDR. Improved production technology?

value in TDRfor both Fermilab and Vladimir

corrected for SiPM internal interpixel x-talk and non-perpendicular incidence

thickness=10 mm

= 7 mm

Both Vladimir and Fermilab strips allow to achieve goal of 99% efficiency at 7.5 pixel threshold at far end..

Module-0 (full size quadrant) The main concerns before starting mass production is - to check geometrical compatibility with support structure, electronics and cabling (to fix all strip sizes) and rigity of the construction; - to elaborate operations for mass production, assembly and installation.

Initial plans: - construct by November’10; - cosmics tests in November, then send to KEK by the end of 2010The start of production was delayed by 2 months. The current status: - all strips and fibers are prepared - gluing of fibers has started (takes ~ 1month) - gluing of strips to substrate (fast operation ~ few days) - support structure will be prepared in ITEP for Module 0 and sent together with scintillator segments to KEK. - technician and engineer from ITEP will come to KEK for assembly after module arrival to KEK (February-March)

Fibers are prepared- cut with actual length- both ends are milled and polished- one end is mirrored- the other glued to connector

Stripswith real lengths are prepared

weldingat junction

- Net of x-y I-bars, where scintillator segments are inserted.- After installation of segments the whole structure is fixed to the existing frame with L-bars, screwed (welded) to the frame.- Preamplifier boards are fixed to the frame.- Al (polyethylene) covers are screwed to the net.- Cables are interlaid in the gap between I-bars net and cover

Support structure5-

9 m

m

frame

x I-bar

y I-bar

Electronics

Current status

The estimated time for whole EKLM production ~ 1.5 year. Should finish production by the end of 2012 Divide the production into several (3) batches to start installation earlier

EKLM Mass production

Check performance with module-0 geometry rigidity assembly and installation

Take decisions: thickness? 7mm -10mm strip producer (Vladimir/Fermilab)

Produce machinery: tool for gluing fiber to the groove (filling groove with optical gel) press for gluing strips to substrate

Buy all necessary materials (at least ⅓ of the whole amount to start) strips (90 k$ for 3.3 tonne (⅓)) Y11 fiber (48 k$ for 12 km (⅓)) SiPM (8 kCh have been bought already (>⅓)) miscellaneous (SiPM housing, optical gel, glue, substrate) mostly available

EKLM Mass productionTo start

we need

Should fix by January’11 to start production in May

Should done by starting of mass production

Fermilab (USA) Vladimir (Russia)

Choose strip producer

Central groove is easier for filling with optical gel (pumping inside), still not clear how to brush groove quickly

Almost identical light yield (with the equal thickness) Almost identical price (~25$ Fermilab; ~28$ Vladimir)

+ 20% for transportation+ 20% taxes (if ITEP buys it, probably taxfree if granted)+ ~40k$ for new die

Production (extrusion) time of whole amount for EKLM = 3 months + 9 months for sawing into strips

Barrel KLM replacement?Can RPC work at higher bg environments?

-At forward edge the low MuId efficiency in barrel can be partially recovered by EKLM- At backward side, where muons are soft, significant loose of acceptance for muon identification

(Y. Yusa)

Can RPC survive for another 10 years of operation?

After disassembling of EKLM. April’11?

Partial replacement (few innermost layers) is very likely;Full replacement... this may happen

Need to prepare design, schedule, think of installation procedure

- barrel ECL cables (only at forward part): mount/dismount from the backward side, except for upper octant (chimney)

- have to remove kite holder. This operation should be very well thought out.

If no full replacement maintenance work is required to reduce dead region.