ATLAS LAr Back-End Electronics Installation X. De La Broise, M. Citterio, L. Hervas, T. Hott, L. Kurchaninov, B. Laforge,

F. Lanni, B. Lund, R. McPherson, V. Paolone

Draft 3.4 09 July 2004

Abstract

This document describes installation procedures of the back-end electronics for LAr calorimeters. We present the operations with cables in the USA15 hall as well as preparation, installation and test procedures foreseen for LAr back-end systems. Manpower and time issues are also addressed.

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1. Introduction The installation of Liquid Argon detectors is basically a sequence of three big activities: (i) cryogenic services and cryostats, (ii) front-end electronics, and (iii) back-end electronics. These three works are performed by different groups of experts and partly separated in time.

The installation and commissioning of the front-end electronics in UX15 is described in a separate Note [1] and not addressed here. From the test point of view, this activity is very complex and requires efforts of many experts in many different fields. The back-end system installation requires fewer efforts. The elements in USA15 are standard sub-racks, like VME crates, computers, standard modules like VME boards or transition modules. Nevertheless, the activities in USA15 are very important. The installation of the back-end subsystems has to be properly scheduled because these are the tools for the front-end crates qualification. The schedule of activities in USA15 is completely driven by the UX15 schedule.

The Liquid argon back-end electronics consists of five subsystems. Table 1 presents different types of sub-racks and modules and Figure 1 shows layout in USA15. In total the Liquid argon back-end system counts up to 156 sub-racks and 819 modules*. This amount of parts will be installed and put to operation during a period of more than a year**, so it cannot be considered as a big amount. The most time consuming operation is not the insertion of units but the testing and debugging procedures.

Most of the back-end elements are custom designed hardware, so the participation of the particular experts will be required in the initial phase of installation. In the routine phase, the experts will be needed only in the case of problems. It is assumed that installation team can do the most part of the work.

In the case of subsystem-specific actions, like deep debugging, the presence of the physicist or engineer with better knowledge of the subsystem is needed during the period scheduled for such kind of actions. And finally, specific experts are needed if a hardware or a software part is not working properly. These experts are called by installation responsible person and should be able to arrive to CERN within a reasonably short time.

The installation sequence of the back-end system can be generally divided to three phases: (i) physical installation, (ii) systematic tests, and (iii) common tests with front-end side. The physical installation includes insertion of sub-racks and modules, cable connections and basic tests to be sure that the parts are operational. The test phase is the full debugging of the subsystem or of its parts. It consists of a set of functional tests and guarantees that the subsystem is ready for use. The last phase, the combined front-end and back-end tests, is a common work of the front-end and back-end groups and is not considered in this Note.

The subsystems layout in USA15, the installation sequence, and details on the tests are described in the sections 3-7. Each subsystem will need to make some pre-installation tests in the electronics maintenance facility (EMF). The activities foreseen in the EMF are also addressed in the following sections. In the Summary we present the organization of the EMF test area as it is seen now.

* In this Note we refer to sub-rack as a unit to be inserted into rack and module as a unit to be inserted into sub-rack ** The schedule is still to be defined, it will basically depend on the delivery of components

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Table 1: Sub-racks and modules of the LARG subsystems in USA15.

Subracks Modules Subsystem Type N Tot Type N Tot Crate 9U 6 Controller 6 Monitor 12 Transition 96

L1

6 Receiver 96 210 Crate 3 Modules 4 DCS Workstation 5 8 4 Crate 9U 17 ROD module 192 Crate 6U 1 TM 192 Workstation 6 TBM 17 Cool station 1 SPAC 31 Cooling units 17 Crate CPU 17

ROD

Patch panel 7 49 Injector 6 455 300V EMB 32 300V EMEC 24 300V FCAL 2 300V HEC 2

LV

Workstation 2 62 0 Crate 6U 22 Purity 2 Workstation 3 EMB 48 EMEC 48 HEC 32 FCAL 16

HV

25 PSEC 4 150 Total 150 819

The other big activity in USA15 is the installation of cables. This work is under shared responsibility of the ATLAS Technical Coordination and Liquid Argon Collaboration [2]. In the next section we describe all those cable operations in USA15 provided by Liquid Argon Collaboration.

According to the present ATLAS installation scenario, the barrel cryostat will stay on the truck until June 2005. In this case there is a few month of access to cryostat and front-end installation can be started on-truck position. In this case the back-end electronics will be connected to front-end crates with a dedicated set of cables borrowed from spare parts.

A rough schedule of the back-end installation is considered in the Summary. As it was mentioned, it is mostly driven by the front-end schedule, which is not completely defined today. The schedule is also determined by the delivery of components, which is not defined today. The time needed for different operations is calculated assuming that one working day

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has 6 pure working hours and one working week is 5 full working days. All the time estimations presented in this Note follow the problemless scenarios.

Figure 1: Racks assignment in USA15 level 2.

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2. Installation of cables All cables connecting LARG detectors and USA15 are produced with double length and with connectors equipped at both ends. This allows the easy installation in the cable chains and passing through the cable holes between UX15 and USA15. Then cables will be cut and equipped with the second connectors in USA15, after the laying down. The LArg team is responsible to organize and carry out the equipping these second connectors. TC will assume the additional costs generated by the fact that this operation is done in USA15 (instead of a workshop or lab).

2.1. L1 trigger cables

The LARG L1 trigger cables deliver analog signals from Tower Builder (Driver) Boards to the Receiver Stations. One cable has typical length of 70 m and is made of 16 shielded twisted pairs with a common protecting shield [3]. In total there are 128 cables for EMB, 112 for EMEC, 96 for HEC and 24 for FCAL that sums up to 360 cables. In addition, there are 14 spare cables placed in the same trays.

The trigger cables are produced by a manufacturer but get functionally tested at Saclay. An automatic test bench has been developed for these tests. A signal, similar to Tower Builder Board output, is injected to one end of the cable and measured at the other end. For each pair, signal shape, amplitude and delay are recorded. The crosstalk between pairs will be also evaluated. The absolute gain and its dispersion between pairs, the peaking time and its dispersion, the propagation time and crosstalk will be determined and compared with tolerance values. Out of specification cables will be returned to manufacturer. Saclay controls also the mechanical aspects of the cable, and fills one data sheet per cable. Cables are labeled by the manufacturer at both sides (each side is marked "A" or "B"), so that it is possible to identify the cables after they are cut.

The test bench consists of a digital oscilloscope, pulse generator, a CAMAC crate with IEEE controller board and two home-made multiplexer-demultiplexer boards (transmitter and receiver). The PC with LabView software controls the test bench, performs the data analysis, compares numbers with specification values, delivers OK/not-OK message and stores cable characteristics. Cables are tested one by one.

This test bench will also be used for the test of the cables after the installation. The way, how to inject signal at the UX15 side is still to be defined. One of the possibilities is to use a dedicated reference cable to deliver signal from the pulser to the cable input.

If a cable does not pass the test, different possibilities can be considered. If an excessive crosstalk or amplitude loss is detected, the second connector should be cabled again on the spot. If a mechanical damage is detected, the cable will be repaired if possible. Otherwise one of the two spares per chain can be used.

The testing procedure for one cable requires about 30 min. Therefore some 12 cables can be tested within one working day. All cables can be tested within 30 days if time is not lost for the cables re-plugging during the tests. It implies that one person is permanently present in UX15 for manual operations and one or two are working in USA15 site.

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The test bench and all specification documents will be provided by CEA-Saclay with manpower to perform tests of the EMB and EMEC cables. The testing of HEC and FCAL cables is the responsibility of MPI-Munich and University of Arizona respectively.

2.2. SPAC and front-end links (B. Lund)

The SPAC signals, both upstream and downstream, of each front end crate controller board are transmitted optically from/to their corresponding SPAC Master board located in the read out crate in USA15. The transmission is inhomogeneous in the sense that the upstream links use 850nm wavelength when the downstream lines use 1310 nm wavelength. These signals are transmitted through multimode optical fibers identical to the ones used to transmit data from the FEB to the ROD boards. FEB to ROD links and SPAC links are bundle in the same lot of fibers. For SPAC purposes, the number of fibers per crate is 8 except for the special EMEC-HEC crates where 12 fibers are needed.

2.3. Readout and TTC links

The RF timing generators are located at the Prevessin Control Room (PCR) and deliver the constant frequency 40.079 MHz LHC bunch clock, a pseudo LHC orbit signal obtained by dividing the clock by 3564, the real SPS orbit signal and the ramping SPS 40 MHz clock obtained by dividing the SPS RF by 5. The PCR transmitters can each broadcast only one orbit and one clock signal simultaneously. The selected pair are encoded and used to modulate a high power laser, the output from which is split by a 1:32 optical tree coupler and broadcast via optical fiber to different destinations around CERN sites over few kilometers. One of the destinations will be ATLAS experiment. These signals are transmitted using monomode optical fibers with a very small jitter (~7ps). Each experiment is equipped with the TTC machine interface (TTCmi), a part of the Central Trigger system.

At that level the signals are duplicated such as to be provided to each partition of the experiment. At the partition level, the trigger and timing signals are transmitted to the LTP module which is interfaced to TTCvi and TTCex modules most frequently coupled to a TTCoc module that fans out the optical signals to the number of desired destinations in the partition. The connections from the TTCex to the TTCoc are optical as the ones from TTCoc to end user boards, namely the FEC controller boards in the case of liquid argon calorimeters partitions.

For each controller board there are two optical fibers connected whereas only one is connected on the TTCoc side. One of these two fibers is installed for redundancy and would need to be connected to the TTCoc of the partition only in case if the first connected one fails. In such a case the two fibers would be exchanged manually in USA15.

Number of TTC fibers to be installed among the 6 LAr partitions is given in Table 2 for front-end destinations and Table 3 for back-end part. All these fibers will be installed by TDAQ community for all ATLAS partitions. This installation will be done in advance to LAr electronics installation.

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Table 2: Front End electronics structure of the Liquid Argon calorimetry and TTC links.

Partition Number of FEC Half Crates Number of Controllers

Number of TTC Links

EMB A 32 (Standard) 32 64 EMB C 32 (Standard) 32 64

EMEC A 16 (Standard) 4 (Special)

16 8

32 16

EMEC C 16 (Standard) 4 (Special)

16 8

32 16

HEC 8 (Standard) 8 16 FCAL 2 (Standard) 2 4 Total 114 22 244

Table 3: Read Out Crate structure of the Liquid Argon calorimetry and TTC links.

Partition Number of RO Crates Number of TTC Links EMB A 4 4 EMB C 4 4

EMEC A 3 3 EMEC C 3 3

HEC 1 1 FCAL 1 1 Total 16 16

2.4. LV lines

Each DC-DC converter that powers the Front-End Crates are powered by 280V power supply modules installed in 8 racks allocated in USA15 through shielded twisted pair cables approximately 70m long. It’s a point-to-point connection (i.e. no bussed distribution of the 280V lines) for a total of 58 cables (32 for the barrel, 26 for the end-cap calorimeters). Additional 8 lines will power the HEC LV boxes.

The cables will be produced in double length, equipped with connectors at both ends and tested:

• The cables will be equipped with the connectors mating the DC-DC converter input connector (Molex Part Nr #####). A mating part will be also installed to prevent from having exposed terminals at any time during installation and routing of the cables.

• Before installation of the cables DC tests will be carried to check continuity and look for shorts.

• Cables will be labeled on both ends with Crate ID (see ATC-OP-QA-0001 for naming conventions) + ATLAS TC-label

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• The cables will be lowered in the pit, cut to proper length and pulled through the cable trays up to USA-15.

• In USA-15 the second connector will be installed. Again DC tests as previously will be repeated.

• Cables will be routed to the corresponding rack/sub-rack and connected. Continuity between the cable shield the power supply case will be also verified.

The time and manpower estimation is detailed in [R4], section 10 2.5. HV cables

The HV units in USA15 are connected to the HV-feedthrough (HV-FT) entrances to the cryostats by multi-conductor (37 wires), double shielded cables (Kerpen, 6KV, 13mm OD). They are equipped at both ends with REDEL-LEMO connectors. Each cable carries 32 independent HV channels and connects one HV module with its mating part on the HV-FT filter crate which is placed directly over the HV-FT. The cables are produced in double length, equipped with connectors at both ends and tested. This operation is done by a subcontractor on CERN site. The tests include connectivity as well as 6 KV HV tests of individual conductors.

Cables are delivered to EMF rolled in caged palettes with ATLAS labels at both ends and connectors protected. Cables are arranged in the palettes (6 double bundles, i.e. 12 cables per palette), which are also labeled. The total number of cables is 54 (Barrel) + 51 (EC-A) + 51 (EC-C) = 156 cables in 13 palettes. The installation sequence should be as follows:

• Lower a palette to the pit floor (crane or lift)

• Un-bundle one-by-one the double bundles in pit and cut at half length

• Pull cables one-by-one starting at FT via cable trays-cable chains, up to USA15-level-2 racks

• Mounting of the second connector in USA15

• Labeling: HV module label + ATLAS-TC label

• HV test of 2 cables by connecting 2 cables at detector end and test system at rack end (could be one reference cable + cable to be tested)

• Route cables on the back and front faces of the USA15 racks (such that individual modules can be removed

• Eventually connect to HV-FT and connect to HV-module

The equipment of connectors and the tests in USA15 will be performed by the same sub-contractor making the cables in close contact with the LAr team. The estimation of time and manpower of this work is done in [R4], section 10. 2.6. DCS cables

LAr DCS has dedicated cables for:

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• CANBus communication and ELMB power (to USA15 DCS rack). These cables are standard items from CERN stores. The ATLAS DCS team is currently considering if the placement of the 2nd connector in USA15 and cable testing should be coordinated centrally for all ATLAS DCS systems.

• Temperature probe cables from FEC to ELMBs. These are cables from Axon. It has been agreed that these cables will be run with both connectors in place. These cables will be tested before and after installation (Orsay).

• Purity signal cables from FEC to USA15 DCS rack. These are standard network cables. The 2nd connector and testing will be done by Mainz.

The estimation of time and manpower for different types of DCS cables can be found in [R4], section 10.

3. Level 1 Receiver Station

3.1. L1 Receiver Description

The receiver system is part of the trigger sum chain and interfaces between the Tower Builder (Driver) Boards and Level 1. One function of the trigger sum chain is to convert the signal from energy to transverse energy. In the case of the EM calorimeters, this conversion is carried out to an accuracy of a few percent, whereas in other cases it is correct only to within a factor of two. The final gain adjustment, therefore, is left to the receiver, which must also account for attenuation in the cable between the Tower Builder (Driver) and the USA15 Cavern. Because of the need for continuously variable gain over a relatively small range, a stage of programmable gain is included in the receiver module. This permits fine control over the calibration of the trigger sum signals, which is useful for the Level 1 trigger. In addition, the signal inputs to the receiver system are either fixed in φ and variable in η or fixed in η and variable in φ. Level 1 requires the trigger sums to be bundled in ∆φ ×××× ∆η bins and this is done via a daughter remapping board located on each receiver module. Finally the system provides for the selection of any of the raw trigger sum signals for the purposes of diagnostic tests, using special monitoring modules locating in the receiver crates.

The receiver chain consists of four op-amps, the first two of which are located on a 16-channel variable gain amplifier (VGA) daughterboard. The third amplifier performs an RC integration, and the fourth op-amp is a driver circuit. The receiver is transformer coupling at both the input and the output, in order to reduce the sensitivity to ground level differences between the detector and USA15, where the receiver crate is located. Each receiver module services 64 such channels, along with circuitry to select channels for monitoring purposes. A detailed description of the functionality of the receiver system is given in [L1].

Each receiver crate contains 16 receiver modules, two monitoring modules, and one controller module. The crate is a standard 9U with a custom backplane, which is used to transport both the digital signals between the controller and the other modules, as well as the analog monitoring signals. The full system consists of a total of 6 (8) receiver crates: 2 for the EM barrel, 2 for EM end-caps, 2 for the forward calorimeters, and hadronic end-caps (plus 2 for TileCal).

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Figure 2: Physical layout of one-half of the receiver system, which services the “ C'' end of the barrel and end-cap.

3.2. L1 Rack and Crate Layout

The receiver crates are located in the Level 1 trigger racks in raw 2, as shown in Figure 1. Figure 2 shows the physical crate layout within the racks for side C of detector. On the far left is shown the rack containing monitoring equipment, then two receiver racks, followed by two preprocessor racks on the right. The second half of the system, which services the end ”A” of the experiment, is identical, except that it is a mirror image of the above layout. Rack numbers 2-5 correspond to rack numbers 7-10 in Figure 1. The “A” end is serviced in rack locations 22-25.

Figure 3 is a schematic drawing of the cabling of signals (trigger sums) onto the receiver system and from the receiver outputs to the Level 1 preprocessor crates. The diagram shows the receivers from one end of the detector, which represents one half of the total system. There will be two receiver crates per rack, so the entire receiver system will occupy four racks.

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Figure 3: Cabling of signals into the receiver crates (four boxes on the left) and from the receiver outputs to the L1 preprocessor crates (four boxes on the right).

3.3. EMF Activities and Requirements

All modules, prior to delivery to CERN, will be thoroughly tested. As modules arrive at CERN, they will pass the simple pre-installation tests for basic functionality at the Electronics Maintenance Facility (EMF) prior to installation into the appropriate crates.

A receiver crate will be permanently stationed at the EMF. The 9U crate will include our custom backplane and a tested crate controller module, to be used for tests and troubleshooting of the receiver and monitor modules. We have ordered 6 new crates in 2003.

One crate will be delivered early 2004 and will be used in the combined test-beam runs. A second crate will arrive mid-year 2004, and be sent to the EMF for use in our receiver test station. In addition to the crate, some control and diagnostic equipment will be needed, such as an ADC/MUX, standalone DAQ system and a control/readout PC. In total we will require enough space for a full sized rack, storage cabinet for spares, and a workbench, in total a 3 ×××× 3 m work area.

The primary purpose of the receiver test crate in the EMF will be to diagnose problems that occur in the system during data taking. At least one technician permanently staffed at the EMF will be trained in the details of operating the receiver test station and correcting simple errors such as replacing daughter-boards or complete modules. This technician will also determine which problems are significant enough to require shipment back to the University of Pittsburgh for more substantial repairs. We will stock sufficient spares in the EMF. Prior to shipment to CERN, the receiver system components will go through rigorous testing. However simple tests, such as channel continuity and control communication checks will be preformed on all incoming modules prior to installation.

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3.4. Receiver Installation

The procedure described in this section assumes that all the needed cables have been installed and the front-end electronics (FEBs and trigger boards) are operating and debugged. Only the final installation in USA15 will be discussed. The installation procedure of the receiver system into USA15 can be broken down into two main steps:

• Physical installation of receiver/monitor modules into crate and cabling

• Testing of individual trigger sum paths and timing study of trigger sums

Then, cabling, both at the input of the receiver modules and at the outputs to Level 1 processor will take place. It is assumed that all the hardware required for cable stress relief has been designed and installed onto the racks prior to this time. Approximately two crates per day can be completed. Therefore a total of up to 2 weeks for the full system is needed. The manpower requirements are two fulltime persons: one senior physicist and one graduate student.

The major amount of time will be dedicated to the checking of the trigger sum cable paths and studies of the relative timing between the four layers that make up a trigger sum and those that are constructed from two physically distinct detector elements such as the barrel and end-cap. In addition, the trigger sum branch and the main data acquisition branch must be tested simultaneously so as to check the data consistency between these two paths. It is assumed that the software and hardware needed for these tests have been written, installed and debugged prior to performing these tasks and that the LARG calibration system is operational and running.

For commissioning, the trigger sum signals are digitized in a special ADC located in the monitoring station VME crate, whose controller will be connected to the ROD system controller via Ethernet. To check that the trigger sum cable paths are correct requires that only individual channels be excited with a calibration pulse at one time. With over 6000 channels of the LARG trigger sums, the process must be automated and not take much longer than ~1 minute per channel. At this time the consistency between the trigger path and the readout path will also be checked. In total 2 weeks involving two fulltime persons will be needed to complete this task.

For the timing studies, blocks of trigger sums can be checked simultaneously; therefore one crate will be tested at a time were only one layer of the total four are excited with a calibration pulse. Assuming this procedure will have to be preformed a few times before the timing is corrected and tested, it could take up to 2 days per crate to complete or approximately 2 weeks for the full system with two full time persons. Both steps of the testing, trigger sum paths and timing, will require dedicated use of the readout and calibration system for about one month with one 8 hour shift per day.

In summary, the receiver installation and commissioning process will require 2 full time persons, one senior and junior level physicist, for approximately 6 weeks. Four of those weeks will require dedicated use of the LARG readout and calibration systems for 8 hours per day. In addition, one person will be needed for technical work for approximately 2 weeks.

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4. Readout Driver System

4.1. ROD system layout

The LARG ROD system is described in a set of documents [R1]. It consists of 16 VME 9U crates and 6 work stations, to be installed in 8 racks in USA15 level 2. The layout foreseen for the ROD system is shown in Figure R1. In order to reduce interference between subdetectors, each partition is placed in separate rack(s) except of two small partitions – HEC and FCAL. The place of workstations is not critical since they are connected through Ethernet. Nevertheless, it is convenient to place WS near the corresponding partition for debugging and commissioning work.

One rack is fully assigned for services – water cooling system and test crate. The cooling system provides water distribution to ROD modules, control and monitoring of temperature, pressure and water flow. The water station and control unit occupy ~20U space in the bottom of rack 10-16. The water is carried to 1U drawers installed on the top of each ROD crate. Each drawer has 4 independent channels distributing water to a group of up to 4 ROD modules. The rest of the rack is reserved for test tools needed for effective diagnostics and debugging during the system installation and commissioning.

The front-end links end up in the patch boxes installed in the bottom of racks 11-16 … 17-16. The cables are split there into ribbons and path through front panel to corresponding crate. They are further split near the crate to individual fibers to be plugged into ROD modules. The detailed description of the patch box design can be found in [R2] and the FEB to ROD connection scheme is available in the ROD installation web page [R3].

Figure R1: Distribution of ROD crates and computers in racks

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4.2. Preparation for installation

All ROD parts arrive to EMF storage area at least one month before installation. In the EMF all parts are labeled and recorded in the installation data base. All modules and crates must pass dedicated pre-installation tests before moving to USA15. These tests include the following steps:

1. Perform basic tests of the crate: water leakage test, power up-down sequences, booting and configuration, temperature and power consumption conditions.

2. Equip ROD crate with all modules corresponding to the configuration to be installed.

3. Test the full crate functionality by injecting predefined input data from Injector modules. It includes the monitoring data flow through VME bus and optical output data transfer. There are only 4 readout channels available in the ROD test bench in EMF, so only one slot can be tested at once.

4. When a crate has passed all tests, the crate configuration is recorded in the installation data base. This is a preliminary record since the crate configuration can be changed later on during tests in USA15.

5. Dismount all modules and power supply units and pack them for the transfer to USA15.

The manpower needed for this work can be estimated as 2 man-days for technical work and 3 man-days for engineer/physicist per one ROD crate.

4.3. Services in USA15

The installation in USA15 will start with water cooling station in rack 10-16 and water pipes mounting in ROD racks. The cooling system has to be functional by the time of the first ROD board installation, therefore this work will be done prior the ROD crates installation. The cooling system will be mounted in 3 steps:

1. Install cooling station, connect to DCS and perform functional tests

2. Mount pipes in ROD racks, check water flow and possible leaks with a simple bypass

3. Install drawers, plug input and output pipes and check couplers for pressure

The next step will be installation of 6 partition masters. The computers are needed in the earliest stage of ROD installation for basic crate tests. Since the ROD installation will last several months, not all 6 PCs will be needed at the same time. Most likely, the computers will be ordered and installed following the schedule of partitions installation. This scenario will minimize the usage of obsolete equipment. The installation of PCs is a well known and well defined procedure. It is basically the system and software installation and configuring.

It is assumed that the external systems, like TTC and LARG DCS are already operational and ready for ROD installation. In the case if readout system is not available, the ROD output data can be read by FILAR cards installed either in one of partition masters or in a dedicated PC placed in service rack 10-16.

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4.4. ROD crate installation

The ROD system will be installed crate by crate following the front-end electronics installation needs. The ROD crate installation is performed in the steps similar to pre-installation tests in section 4.2:

1. Mount crate and power supply, connect water pipes to LV unit and check water leak and flow. Connect to ground and mains, check temperature and consuming power

2. Connect crate CANBus line to LARG DCS work station and make CANBus functional test

3. Install CPU and perform basic VME tests

4. Install injector, TBM and SPAC modules, and check their functionality. Connect TTC lines and test the signals distribution. Check SPAC functionality

5. Equip ROD crate with selected ROD and TM modules. Connect Glink cooling pipes and check Glink temperatures and crate power consumption

6. Make tests of ROD VME access and VME data transfer

7. Test the crate functionality by injecting input data from Injector module and reading optical output data

The last two tests are not completely defined today. They will be better specified after gaining experience from back-end crate system test, beam tests performed in summer 2004 and first pre-installation tests in EMF.

The manpower and required for full ROD installation can be found in LARG Installation Tasks and WP table [R4], section 7. In total the estimation is 87 technical man-days and 116 man-days of engineer or physicist for all partitions. These numbers do not include the common front-end and back-end parts commissioning.

5. High voltage system

The Lar HV system [H1] is housed in sub racks located on USA-15 level 2. Five racks are needed to hold all crates and ancillary equipment. Their foreseen layout is sketched in Fig. H1. The sub-racks are air cooled in the closed racks. We rely on the heating power extraction by the water cooling circuit of the rack heat exchangers.

The sub racks house HV units (at most 8 in each) each one delivering 32 independent HV channels on one multi-pin REDEL-LEMO connector. Each HV unit is controlled by 2 CAN nodes each one serves 16 channels. Thus a group of four sub-racks completely fills the address space (0…63) of one CAN-bus line. The CAN bus lines are driven by three PC’s equipped with PCI-CAN interfaces, each one running two separate CAN lines.

The PCs (atlar-hv1,2,3) are 19” rack mounted housed in the same racks as the HV sub-racks. One additional PC (atlar-hv0) serves as disk data server for all three others. The configuration will be most probably of one client (hv0) communicating with the servers

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running in the hv1,2,3 machines. These serve the data points of the HV modules seen by the two CAN bus lines.

In addition to the USA-15 system, the installation of the HV filter boards on the cryostat HV feedthroughs need to be performed. They are mandatory to perform any HV test on the calorimeters. The first HV test will happen immediately following the cryostats transport and lowering.

The following activities are foreseen in EMF:

• Shipment to CERN. All HV sub-racks and modules are currently at CERN, with most of them being in use in the integration effort in B180.

• Storage in EMF The HV modules and sub-racks will be labeled with ATLAS identifiers and functional labels. They will be declared in the e-production DB and in the ATLAS installation DB.

• Pre-installation tests. No further tests are foreseen at this point. However, one crate, equipped with an absolute calibration system will be available for periodic precision recalibration of the HV modules and individual module debugging.

Figure H1: Layout of HV racks

RACK A2 RACK A1 RACK B RACK C1 RACK C2

SR 4 EMEC A

SR 6 HEC A

SR 20 ECCA/C-PS

SR 12 HEC C

SR 10 EMEC C

SR 3 EMEC A

SR 5 HEC A

SR 19 EMB-SP/ ALL-PUR

SR 11 HEC C

SR 9 EMEC C

MIXED PANEL

SR 2 EMEC A

SR 14 EMBA

SR 18 EMBC-PS

SR 16 EMB C

SR 8 EMEC C

SR 1 FCAL A

SR 13 EMBA

SR 17 EMBA-PS

SR 15 EMB C

SR 7 FCAL C

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The HV system should be installed in one go. Since however some sub-racks are needed in B180 for testing the cryostats, probably a partial system (sub-racks and modules not in use there) will be installed first and tested in USA-15 long before any USA-15/UX-15 cables are available.

We estimate a total of 8 days by a 2 person team required for physical sub-rack and 15 days for module installation. Other minor points to be covered are the installation of the control PCs and their connections to network. Basic tests include powering and cooling verification. CAN communication with the PCs needs to be verified.

Tests will be done in two steps. First the HV system as such needs to be operational with its multi level client-server control software. After cabling has been setup and routed to the racks front faces, connections are made to the HV feedthroughs on the cryostats. Only then, full commissioning takes place, first with (lower) HV values while the cryostat volumes are filled with gas, later with HV when in LAr. This process is repeated with each one of the three cryostats.

6. Low voltage power supplies The low-voltage power supply system consists of 60 independent power units: 58 for FECs and 2 for HEC LVPS. Figure LV1 depicts a block diagram of the subsystem powering the 58 Front-End Crates [LV1]. The same applies to the 2 HEC LV PS boxes (see [LV2] for a detailed description of the system).

8 racks are allocated in USA-15 level 2 for the power supply distribution. The layout of the racks will be implemented so that each of them will power only Front-End Crates (or HEC LVPS boxes) from the same calorimeter side for a total of 4 logic partitions. More precisely:

• Rack 16-22: 8 280V units for EM Barrel side A

• Rack 16-23: 8 280V units for EM Barrel side A

• Rack 16-24: 8 280V units for EM Barrel side C

• Rack 16-25: 8 280V units for EM Barrel side C

• Rack 16-26: 7 280V units for EC side A

• Rack 16-27: 6 280V units for EC side A and 2 units for the HEC LV

• Rack 16-27: 7 280V units for EC side C

• Rack 16-28: 6 280V units for EC side and 2 boxes for the HEC LV

The detailed layout of each rack including the location of the ventilation, fan trays and heat exchanger units has still to be determined and will depend on the final mechanical specifications of the 280V PS modules.

The following activities are foreseen in EMF:

• 280V PS units will be delivered directly from the manufacturer to CERN. The manufacturer will deliver with the unit a Production Unit Traveler Sheet proving the conformity of the unit to the specifications

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Figure LV1: Low Voltage PS system layout for the Front-End crates.

• Each unit will be labeled and data inserted in the Electronics Production Database

• Each unit will be stored and tested at CERN before installation. The tests will include:

o Power-up/down sequence at the nominal settings with determined load o Test of the monitoring and control functionalities (voltage and current

monitoring, GND fault detection, interlock activation) o Test results at EMF will be also included in the Electronics Production

Database

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Installation of all the units of the 4 logical partitions should occur at once. However final tests are conditional to the installation of the LV DC-DC converters as well as to the installation of the Front-End Crate boards in UX-15, therefore tests should be organized by partitions and coherently with the testing of the Front-End Crates.

Here follows a short description of the installation sequence:

• Rack preparation and mechanical installation of the 280V units:1 tech for 8 days

• Routing and installation of the DCS interface: 1 tech for 4 days

• DCS tests:1 phy/eng. during 4 days

• Routing and connection of the 280V PS cables (including second connector installation and basics tests): 1 tech during 5 days

7. LAr detector control system The LAr Detector Control System (DCS) system is described in [D1]. It will be a hierarchical system with components located inside the cryostats, in the front-end crates, in the tile-calorimeter finger regions, on the cryogenics platform in UX15 and in the LAr DCS rack in USA15. These components are integrated into the complete monitoring and control system, which is intended to maintain safe and reliable operation of the LAr calorimeter.

The principal LAr DCS tasks are:

1) Overall LAr subsystem DCS control, interactions between LAr DCS and DAQ, database writing

2) Module temperature monitoring

3) Liquid Argon purity monitoring

4) FEC low voltage monitoring and water cooling monitoring

5) 280 Volt power supply monitoring and control (see section 6)

6) HEC low voltage electronics power supply monitoring and control

7) High Voltage power supply monitoring and control (see section 5)

Figure D0: Layout of the LAr DCS rack 16-18

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The LAr DCS system makes heavy use of the Embedded Local Monitoring Board (ELMB) developed by the ATLAS central DCS team. It is a multi-purpose board with analogue, digital, and CANBus sections. The analogue section has 64 differential ADC channels, used in LAr for monitoring voltages and PT100 temperature-sensitive resistors. The digital section contains a CPU, which controls the functions of the ELMBs, and also contains a number of digital input/output channels. The CANBus section is used to configure, control and readout the ELMB. These three sections are optically isolated, and can be powered independently.

The LAr DCS system makes heavy use of the Embedded Local Monitoring Board (ELMB) developed by the ATLAS central DCS team. It is a multi-purpose board with analogue, digital, and CANBus sections. The analogue section has 64 differential ADC channels, used in LAr for monitoring voltages and PT100 temperature-sensitive resistors. The digital section contains a CPU, which controls the functions of the ELMBs, and also contains a number of digital input/output channels. The CANBus section is used to configure, control and readout the ELMB. These three sections are optically isolated, and can be powered independently.

The LAr DCS system uses rack 16-18 in USA 15. The layout of this rack is shown in Fig. D1. The EMF will not be used heavily by LAr DCS, and most of the components will already be present at CERN before the start of installation. Most of the LAr DCS subsystems will be developed and tested in the FEC tests at BNL, detector cold tests in Building 180, or the 2004 combined beam tests.

The LAr DCS system will be installed and tested one subsystem at a time, with each system running independently. The FEC low voltage monitoring and control will in particular be operational during the complete LAr electronics installation period. A possible installation and testing sequence would be:

Overall LAr DCS (one person for 6 months initially, plus continuous availability during installation period)

• Install PVSS workstation in LAr DCS rack in USA15 • Install CANBranch/ELMB power crates in USA15 • Test communication with LAr DCS LCSs, when possible • Test communication with ATLAS global GCS workstation • Implement all data points exchanged with LCSs and GCS • Implement communication with LAr DAQ systems when possible • Complete implementation of DCS finite-state-machine protocol • Define user display and interaction panel in PVSS

LAr module temperature monitoring (1-2 people for entire 1 month initially, plus one person during each temperature FEB installation, and availability during cool down)

• Install PVSS workstation (Temperature LCS) in LAr DCS rack in USA15 • Install ELMBs in cryostat platform area • Install ELMBs in EC FEC region when possible • Test communication between ELMBs and Temperature LCS computer

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LAr purity monitoring (1-2 people for entire 1 month initially, plus 1 person during each purity FEB installation)

• Install PVSS workstation (purity LCS) in LAr DCS rack in USA15 • Install purity crate and electronics in USA15 • Test communication between front-end and back-end boards, and with purity

LCS

FEC and 300-volt power supply monitoring and control (1-2 people for entire FEC installation period)

• Install PVSS workstation (FEC LCS) in LAr DCS rack in USA15 • Install ELMBs in FEC PS area, including cabling of CANBus lines to USA15 • Install ELMBs in USA15 for 300-volt PS monitoring and control • Test communication between ELMBs and FEC LCS computer • Test readout and control lines between ELMBs and power supplies

HEC LV system monitoring and control (1-2 people for 1 month for each EC) • Install PVSS workstation (FEC LCS) in LAr DCS rack in USA15 • Test communication between HEC PS “boxes” and HEC LCS computer

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8. Summary

8.1. Back-end test benches in EMF

The minimal needs of test equipment in EMF dedicated for back-end subsystems are shown in Table 2. In total three test benches can be located in 4 racks. Extra working space is needed for 5 computers. These benches are used for preinstallation tests of back-end electronics and provide control, readout and monitoring of corresponding front-end parts.

Table 2: EMF test benches for back-end electronics.

Subsystem Racks Crates PC Function L1 1 2 1 Tests of receivers, TBB, TDB and L1 cables

ROD 2 2 2 ROD tests, FEB checks HV 1 1 Tests of HV modules and crates LV 1 0 Tests of LV supplies, FEC

DCS 1

0 1 DCS tests, support all benches in EMF

8.2. Manpower estimation for installation in USA15

Table 3 presents the summary of manpower estimations for operations in USA15. The common work with front-end installation crew is not included here.

Table 2: EMF test benches for back-end electronics.

Technical Engineer/physicist Subsystem Person Day Man-day Person Day Man-day

L1 cables 3 60 180 3 60 180 FE links

HV cables 1-2 39 72 1-2 24 42 LV cables 1 11 11 1 4 4 DCS lines

L1 1 10 10 2 30 60 ROD 1-2 50 87 2-3 50 116 HV 1-2 38 61 2 26 52 LV 1 14 14 1 14 14

DCS Additional time and manpower are needed for tests and preparations in EMF. It is difficult to make a reliable estimation for this work since most of the preinstallation tests are not specified today.

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References [1] LAr FE electronics installation [2] The responsibility table is posted at the ATLAS Installation web area:

http://atlas.web.cern.ch/Atlas/TCOORD/Activities/TcOffice/Scheduling/Installation/ LAr_inst_resp.html

[3] L1 trigger cables PRR

[L1] W.E. Cleland, B. Liu, J. Rabel, and G. Zuk Receiver/Monitor System for the ATLAS Liquid Argon Calorimeter. CERN EDMS Document ATL-AL-EN-0043 v.3. [R1] LARG ROD system design review 02 Feb. 2004 http://wwwlapp.in2p3.fr/~poggioli/review [R2] LARG front-end links patch boxes [R3] LARG FEB to ROD connections [R4] LAr Electronics & Cables Installation Tasks

http://atlas.web.cern.ch/Atlas/GROUPS/LIQARGSTORE/II/Installation /LAr_Elec_Cab_Inst.pdf

[H1] http://atlas.web.cern.ch/Atlas/GROUPS/LIQARGON/Electronics/ Power_Cooling/

HV_supplies/HV-Channels_ALL.htm [D1] LAr DCS System Overview, 3 Feb 2004. See: http://atlas.web.cern.ch/Atlas/GROUPS/LIQARGON/Electronics/Monitoring/ [X] ATLAS installation schedule web page http://atlas.web.cern.ch/Atlas/TCOORD/Activities/TcOffice/Scheduling/Installation/

installation_schedules.html