Status of OPERA RPC production. A. Garfagnini Opera collaboration meeting Nagoya, 12 march 2002  RPC production at GT;  Schedule for OPERA in 2002;  Summary of the quality control tests:  results from the OPERA prototypes;  Status of LNGS infrastructures for RPC mass production tests.

A.Garfagnini – page 2 General Tecnica (GT) s.r.l. Company located at Colli (Frosinone), ~120 km south-east of Rome. Producer of tooling for assembly lines for cars radiators (working mainly for the FIAT factory near Cassino). Unique producer of bakelite RPCs in Italy. Past productions: L3 (~ 600 m 2 ) and BABAR; Running productions: BABAR, ARGO, ATLAS, CMS, ALICE, OPERA, … Factory owner and technical director: Mr. Fabrizi. Responsible of production and quality control: Mr. Fiore. ~10 technicians are currently involved in the RPC assembly and strips preparation and integration. RPC production buldings ~ 700 m 2

A.Garfagnini – page 3 RPC production history (2001) All the bakelite RPCs for the INFN experiments are produced by General Tecnica. In order to coordinate the experiments needs, a INFN committee had been formed, with the task of analyze and improve the processing procedure and to interact between the INFN and the factory. After a successful benckmark performed last year, the company produced 12 RPCs/day, on average, for one month. The BABAR experiment had a key role in the development and improvements of the production.

A.Garfagnini – page 4 RPC production (2002) This year the production has been boosted to 18 RPC/day in order to fulfill all the requirements (mainly dominated by the LHC experiments); new tools and procedures have been introduced: the gluing step has been automated, the glue curing places - “pizzeria” – have been doubled, and a new building for the storage of the materials is under construction. The committee, lead by S.Morganti (INFN Rome-1 st university and BABAR), has regular meetings where production schedules and results are discussed; each experiment has at least one representative person which is contact with the committee and follows its RPCs production at General Tecnica (next meeting, march 14 th in Rome).

A.Garfagnini – page 5 RPC production (1) According to the above schedule OPERA production will start in June 2002; 574 RPCs will be produced by the end of 2002, (always < 30% of the total share/month).

A.Garfagnini – page 6 RPC production (2) The offer for the OPERA production is at the moment in a stand-by position, as many of the spectrometer components. Nevertheless, the first set of bakelite (105 layers, high resistivity from BABAR) has been received and inspected at GT: 16% rejected due to same production defect (feedback w/ PanPla needed). New layers expected soon (build a buffer at GT and LNGS).  Once the CERN and INFN positions will become clear, ready to start.

A.Garfagnini – page 7 Quality control tests The OPERA quality control checks are strongly based on those developed for the BABAR experiments (S.Morganti, et al. They can be classified into: mechanical tests: gas tightness (leakage) and spacers gluing (first bubble + push); electrical tests: HV conditioning and IV curves. response to elementary particles: chamber radiography and efficiency curves. All the quality control tests will be performed at the Gran Sasso laboratories (LNGS), where a dedicated hall (lab2) has been assigned. Results on the QC tests for the prototypes, performed at GT using the BABAR equipment, are summarized in the followings.

A.Garfagnini – page 8 OPERA prototypes o16 full-size prototypes have been produced by the end of 2001; o1 has been used by GT to check the oil coating quality; o1 rejected due to bakelite defects (used as dummy for test calibration); o2 rejected during mechanical tests; o12 chambers pass the quality controls (12/15  0.8): 9 sent to CERN; 3 to LNGS.

A.Garfagnini – page 9 Mechanical tests summary (1) mechanical tests:  no gas leakage found;  for one chamber spacers disconnect while inflating;  one chamber is spoiled during test, human error, (water fills the gap).  The two rejected RPCs have been opened to check oil coating. First spacer, “pops” at 15 and 70 mbar (water filled chamber).

A.Garfagnini – page 10 Push test AIM: Identify and localize unglued spacers (can cause inefficiencies). The GAP with internal pressure will experiment a small deformation in the presence of an unglued spacer. The deformation is neutralized with small cylinders (9/row) which are moved across the chamber. The pressure sensor will detect a small volume deformation due to one ore more unglued spacers and spacers glued away form the nominal position.

A.Garfagnini – page 11 One tested chamber had several unglued spacers (no glue on one side was find after having opened the chamber. The final test will be completely automated, reducing the operator time and improving the sensitivity of the test. Push test results

A.Garfagnini – page 12 Electrical tests summary The chambers are filled and fluxed w/ gas for some time (time required to exchange several gas volumes) before the first IV curve is performed. An I/V curve is performed from 0 to 8 kV (up to 7kV for the prototypes). Dust residuals are “burned” keeping the GAP for some time at fixed voltage. Annealing effect is seen for IV curves measured at different times.

A.Garfagnini – page 13 Cosmic rays tests  Boxes A cosmic test station is being setup. Big involvement for the LNGS electronic and mechanical workshops, lead by C.Gustavino and L.Tatananni, respectively. Trigger: 2 planes (4  4 m 2 each) using glass RPCs; 1 cm strips (flat cables glued on polypropylene); 1 st coordinate, digital readout (MACRO GSC cards); 2 nd coordinate using time information (  t < 50 ps). Bakelite RPCs: 3 boxes (12  3) under test at once; use MACRO readout strips (3 cm) for both coordinates; digital readout (MACRO GSC).

A.Garfagnini – page 14 LNGS infrastructures Experimental hall free for OPERA; Started the process for the offers for the gas system (4 independent distribution point inside the hall – gas mixed inside); Trigger planes: Mechanical structure in advanced status, started to mount the structures inside the hall; RPCs: glass delivered, start to assemble the detectors (16 m 2 ); material for strips (flat cable + polypropylene planes) available; electronics for t 1 -t 2 under testing, final production will start soon. RPC under test: measures fixed, 2 box prototypes ordered; material for strips available (from MACRO); card for signal inversion (HV = ± 4kV) designed, prototypes will be soon available for testing.

A.Garfagnini – page 15 LNGS infrastructures (2) DAQ under development, will use a system similar to that currently used for MONOLITH prototype and for GSC-II project), will start to exercise with the OPERA RPC prototypes available at LNGS. For the mechanical tests work is underway: automatic push test prepared by E.Buccheri (Roma1 technician, temporarily assigned to the project). Readout and analysis programs under development. Idea to provide a database, with web interface, storing all the tests parameters, up to the RPC radiography.

A.Garfagnini – page 16 Summary The QC steps have been defined and work has started; some months are needed before the system is fully assembled, the software completed and debugged and the system becomes fully operational for the mass production control. We are thankful to the BABAR collaboration, in particular to S.Morganti, for their help; we have learned from their experience and selected a QC system which is essential for the large production of the OPERA RPCs (more than 1500 GAPs). The LNGS technical support has been very cooperative and is essential for a successful realization of the whole QC machinery.