CMS GRPC detector& cassette I. laktineh

Concepts Two concepts of RE1/1 detectors were developed : 1- One based on gluing glass plates to have large RPC. The cassette in this case is identical to the CMS one 2- One based on building small RPC assembled mechanically to have large one. The small RPC have no walls. The gas tightness is provided by the cassette in this case. We think the second concept is more robust.

Gas-tight cassette concept 3  Two-gap  30 cm x30 cm max. size  Open small chambers&”closed” cassette  Different size of small chambers in the two gaps to eliminate dead zones  Spacer : tiny fishing lines inside PEEK pearls to reduce the loss of efficiency

Mechanical drawing Lateral spacers to keep tight the two gaps and for fishing lines stretching

Small RPC sizes: bottom gap (S. Cauwenbergh)

Small RPC sizes: top gap (S. Cauwenbergh)

Silk screen printing

4,5 ≤ résistivité (M.Ω/ ⃞ )≤ 12 Silk screen printing

Back plate : Alum Cover : Alum Walls : Alum Cassette construction

To ensure gas tightness an O-rings of 0.4 mm compressibility is used

Gas-tight signal transmission connectors

NorComp 48-channel connectors

Pieces to maintain tight the small detectors and to stretch fishing lines are made from Nylon Fixation pieces

Fil Spacers Spacers are made of pieces of hollow PEKK tubes (pearls) with fishing lines of

83 PEEK pearls (Trans Luminal) L = 12 mm, Ext. Diam. 1,2 mm (+0 mm/ -0,02 mm), Int. Diam int 0,5 mm Fishing lines (nylon) : Diam = 0,4 (+0,02/-0)

Conductive Epoxy CW2400 (Chemtronics) + very thin copper tapes for high voltage connection of different glass plates

With the CMS strip PCB

PEEK pearls for the top gap

To ensure tightness and good contact between the gaps and the PCB a (PC) plate with springs was machined and used. 10 mm 2,5 mm 1.Ensemble CH Glass = 3,8 Kg 2.Plaque d’appui en PC = 3,25 kg 3.PCB = 0,3 Kg 4.Mylar inter chambre = 0,2 Kg 5.Capot = 8,9 Kg 6.Surface = 1 m 2 7,55 Kg + 30% sécurité = 9,815 Kg → 96,25 N + 40 % = 10,57 Kg → 103,65 N + 50 % = 11,325 Kg → 111,06 N + 75 % = 13,175 Kg → 129,20 N % = 15,1 Kg → 148,08 N LO : long à vide mm L1 : long en charge 5mm ≤ L1 ≤ 8,5 mm K : raideur N/mm P1 : Pression à L1 12 ressorts : 8,02 N ≤ P1 ≤ 12,34 N Moyenne : 10,18 N Formule : P1= k (L0-L1) kgf = 9, N 12 inox springs

Once the spring plate is put on the two-gap detector the cover is placed and screwed. Final step

Conclusion  First gas-tight cassette with large 2-gap RPC is built and successfully tested  Thickness, material budget and dead zones are to be studied and improved with the new electronics.  Another cassette with the same structure using low- resistivity glass is being built and could be placed in GIF++ in 2016  We would like to work on RE4/1, RE3/1 and RE2/1 mechanical structures in the future.

Fixation pieces