ID:13
Corresponding Author: Pavol STRIZENEC
Experiment: ATLAS
Sub-system: Calorimetry
Topic: Electronics for Calorimeters

Calibration of the ATLAS Hadronic End-Cap Calorimeter

H. Brettel, W.D. Cwienk, L. Kurchaninov, H. Oberlack, P. Schacht
(Max-Plank-Institute for Physics, Munich, Germany)

A. Jusko, P. Strizenec
(Institute of Experimental Physics SAS, Kosice, Slovakia)

On behalf of the ATLAS HEC Collaboration

Abstract:

The calibration chain of the ATLAS HEC is described. A model based on detailed studies of all individual parts is presented.

The characteristics of the steering and data taking system for both the test-beam runs and for the acceptance tests of the HEC modules is summarized.

The calibration and signal reconstruction procedure is developed and results of the test-beam data are presented.

Id: 37
Corresponding Author: Bertrand LAFORGE
Experiment: ATLAS
Sub-system: Calorimetry
Topic: Electronics For Calorimeters

Implementation of a Serial Protocol for the Liquid Argon Atlas Calorimeter (SPAC)

F.Hubaut, B.Laforge, O.Le Dortz, D.Martin, Ph. Schwemling
LPNHE Paris

Abstract:

The Serial Protocol for the Atlas Calorimeter (SPAC) has been designed to provide the loading and reading of all parameters of the front-end boards of the ATLAS Liquid Argon Calorimeter.

This single master / multiple slaves serial protocol is designed to be transmitted optically and electrically, at up to 10 Mbits/s, and enables broadcast or individual transfers from the master to one or a set of slaves.

Some test results about the SPAC performance and its implementation within the ATLAS framework will be presented.

Summary:

The Serial Protocol for the Atlas Calorimeter (SPAC) has been designed to provide the loading and reading of all parameters of the front-end boards of the ATLAS Liquid Argon Calorimeter.

This single master / multiple slaves serial protocol is designed to be transmitted optically and electrically, at up to 10 Mbits/s, and enables broadcast or individual transfers from the master to one or a set of slaves.

One SPAC network, controlling one front-end crate, includes one master module in the counting room and slave ASICs, made in DMILL technology and housed on each front-end board. The slaves integrate a I2C master interface and a parallel interface to be exploited by the boards.

Some test results about the SPAC performance and its implementation within the ATLAS framework will be presented.

Id: 44
Corresponding Author: Julie PRAST
Experiment: ATLAS
Sub-system: Calorimetry
Topic: Electronics For Calorimeters

THE ATLAS LIQUID ARGON CALORIMETERS READ OUT DRIVERS

Julie Prast for the ATLAS Collaboration

Abstract:

The Read Out Driver (ROD) for the Liquid Argon calorimeters front-end electronics of the ATLAS detector is described. Those ROD modules are designed for the ATLAS electromagnetic, hadronic end-cap and forward calorimeters. Each ROD module receives data from two Front-End Boards (FEB). The FEB amplifies, shapes, samples and stores the signal from 128 calorimeters cells at the frequency of the LHC (40 MHz). Then, the data are digitized and sent to the ROD modules for each Level-1 trigger (maximum rate of 100 kHz). These data are transmitted by two 32 bits data optical links. The principal function of the ROD is to reconstruct the precise energy and timing of each cell signal from the time samples. In addition, the ROD checks and histograms the data. The treated data are then sent towards the Read Out Buffers (ROB), according to a defined format, where they are stored.

A demonstrator system consisting of a mother board and several daughter boards Processing Units (PU), is under development. The goal of the demonstrator is to prove the feasibility of the project and serve as an intermediate step towards the construction of the final ROD module for the ATLAS experiment. The design of the prototypes are presented here.

The mother board is a full size 9U VME module able to carry four daughter boards. It allows all the input/output connections with the FEB and ROB, the controls of the board and the VME interface. This board offers maximum modularity and allows the development and testing of different Processing Units (PU). Three PU are being studied. Two are designed with the Texas Instrument TMS320C6202 fixed point DSP, while the other one is designed with the Analog Devices 21160 floating point DSP. These PU present the same overall architecture. The example of the Analog Devices PU will be taken.

Each PU treats data from an half FEB (8 ADC). Each ADC digitizes signals from 8 calorimeters cells. Each channel is composed of five 12-bit samples. These FEB data enter an FPGA at the speed of 40 MHz They are parallelized, parity checked and formatted before being buffered into the internal FIFO of the FPGA. This FIFO is connected to the external memory bus of the DSP. Once the DSP finishes the processing of the event, the results are formatted according to the ROB format and then put into a FIFO. This output FIFO is read by the mother board Output Controller.

The PU also contains a communication port, through which all the control of the board is done. It uses the DSP link ports to communicate with the mother board VME interface. It is also used to send monitoring or debugging information to the local CPU. All the communications between the DSP and its peripheral are done by Direct Memory Access (DMA), thus being transparent for the DSP core.

Results for the different PU will be presented and compared (functioning, performance, DSP algorithm). The first tests have shown that the demonstrator board meets the ATLAS requirements in term of bandwidth and accuracy, although the DSP used are not the next generation of DSP foreseen for the final version of the board.

Corresponding Author: Angel DIEGUEZ
Experiment: LHCB
Sub-system: Calorimetry
Topic: Electronics For Calorimeters

A BiCMOS discriminator interface for the SPD

A. Diéguez, S. Bota Departament d'Electrònica, Sistemes d'Instrumentació i Comunicacions, Universitat de Barcelona, C/Martí Franquès, 1, E-08028, Barcelona. Spain

D. Gascón, L. Garrido Departament d'Estructura i Constituents de la Matèria, Universitat de Barcelona, C/Martí i Franques 1, E-08028 Barcelona. Spain.

M. Roselló Departament d'Electrònica, Enginyeria i Arquitectura La salle, Universitat Ramon Llull, Pg. Bonanova 8, E-08022, Barcelona. Spain.

Abstract:

A prototype chip for the analogue readout of the SPD in the LHCb Calorimeter is presented. The chip has been designed using the 0.8mm-BiCMOS technology of AMS and optimised for minimum size and maximum performance at the required frequency of operation in LHC experiments. It consists of a dual structure formed by two integrators, two track and hold circuits, two substractors, two comparators and a multiplexer. The die size occupied by one discriminator circuit is approximately 1720 mm x 330 mm.

Summary:

The microelectronic circuit designed is a pulse discriminator interface for the Scintillator Pad Detector (SPD) at the Electromagnetic Calorimeter (ECAL) at LHCb. It has to operate at the L0 trigger level of LHC (f=40MHz, T=25ns) to detect the signals from electrons at the SPD, discriminating the signal originated by photons (background). The signal entering the discriminator is originated at the SPD, transmitted through an optical fibre and amplified in a photomultiplier. The jitter of the input signal makes better to integrate it rather than consider its maximum value. So, the first block of the discriminator is an analogue integrator. On the other hand, because of the shape of the input signal, only its 83% is integrated in 25ns. This mandates the use of at least a dual architecture (two channels in each discriminator) in order to allow the substration in the current period of the 17% of the signal integrated in the previous one. A dual architecture avoids also to have dead time on integration. The integrated value to be substracted is stored in a track and hold. After the substraction, a comparator with tunable treshold gives a logic signal indicating an interesting event to be stored in the experiment. The last signal is finally multiplexed.

So, each channel of the discriminator comprises an integrator, a track and hold, a substractor and a comparator. The output of the discriminator is obtained through a final 2/1 differential multiplexer. In the prototype chip all blocks have been included separately and two different discriminators. Each one of these discriminators corresponds to two different integrator circuits. The circuit is fully differential in order to reduce noise effects. All the blocks in the circuit are biased between 2.5V and -2.5V, and polarisation currents are lower than 250mA in all blocks. The circuit has been implemented with the 0.8mm-BiCMOS technology of AMS in order to have the required frequency of operation. Because of the large number of channels to process (6000), the design has been optimised for minimum area. Each discriminator circuit, including the routing area and clock distribution is about 1720 mm x 330 mm.

It will be presented a detailed description of each block in the discriminator, as well as their functional behaviour and the final performance of the entire discriminator.

Id: 65
Corresponding Author: Christophe de la Taille
Experiment: ATLAS
Sub-system: Calorimetry
Topic: Electronics For Calorimeters

Overview of the ATLAS LAr front-end radiation tolerance

C. de La Taille (LAL Orsay)

Abstract:

The front-end electronics of the ATLAS liquid argon calorimeter must withstand a non-negligible radiation environment (20Gy/yr 5e11N/cm2/yr), in particular when various safety factors (simulation inaccuracies, lots variability or low dose rate effects) are put on top. The design of all the front end elements is now complete and has been tested on module0 on over 2,000 channels. Several key components have been extensively tested to radiation exposure (preamps, shapers, pipelines...) whereas other circuits (mostly digital) are being now migrated into DMILL. The results of these tests will be summarized and the design of the DMILL chips will be presented. The next milestone of the LAr collaboration is to have a final radiation hard complete front-end prototype by mid july.

Id: 72
Corresponding Author: Dezso NOVAK
Experiment: CMS
Sub-system: Calorimetry
Topic: Electronics for Calorimeter

Radiation hardness studies for CMS HF quartz fiber calorimeter

G. Dajkó, A. Fenyvesi, K. Makónyi, J. Molnár
Atomki, Debrecen, Hungary

P. Raics
University of Debrecen, Debrecen, Hungary

I.Dumanoglu
Cukurowa University, Adana, Turkey

J. P. Merlo
University of Iowa, Iowa City, USA

A Kerek, D. Novák
Kungl Tekniska Högskolan, Stockholm, Sweden

Abstract:

A project has been in progress to provide information on radiation hardness properties of Hamamatsu photomultiplier tubes and quartz-fibers to be used in the construction of CMS Very Forward Calorimeter. Neutron activation studies as well as neutron, gamma and electron radiation tolerance tests have been carried out, using 3.7 MeV average energy neutrons, 500 MeV energy electrons and Co-60 gamma radiation. The test setups, the irradiation conditions as well as the experimental results are described.

Summary:

Introduction

Very Forward Calorimeters (VFCs) in LHC detectors cover the pseudorapidity range from 2.5 to at least 5 in order to compute missing transverse energy and for jet tagging. The forward calorimeter (HF) in CMS will experience unprecedented particle fluxes. The 10 years of LHC operation will result in about 1 GRad total dose. Operation at such conditions requires the use of calorimetry technique that is insensitive to radiative load.

The CMS HF is based on the quartz-fiber technology, using silica-core and silica-clad fibers as the active component. This choice was based predominantly on their exceptional radiation resistance. In such a calorimeter, the signal is detected when charged shower particles above the threshold generate Cherenkov light.

The read-out of the light from the fibers are done by UV sensitive photomultiplier tubes (PMT).

The purpose of this paper is the presentation of the performances of the different kinds of silica fibers and ultra-violet photodetectors in the presence of radiation. We focused on a shorter wavelength region between 325 and 800 nm under an irradiation field, with special attention to the PMTs sensitivity range, 400 to 500 nm.

Test facilities and conditions

An IBM-PC based Ocean Optics Model (SD 2000 type) spectrometer with a pulsed Xe lamp was used for all fiber related measurements. One part of a Xe light pulse goes directly to the spectrometer as a reference. The second part is sent to the fiber sample under irradiation. This setup allows in-situ measurement of the fiber darkening. We performed measurements at two different facilities: at the LIL. The LIL , LEP pre-injector at CERN provides a 500 MeV electron beam on the target.

In the fast neutron tests at ATOMKI in Debrecen, Hungary the MGC-20 cyclotron based neutron source was used generating neutrons with an average energy of 3.7 MeV.

All the HAMAMATSU PMT tests - gamma, neutron, and activation - were carried out at ATOMKI.

Analysis and results

The expression for the light attenuation of the fibers can be written as:

A(l)=Ao(l)-(10/L)log(Iirr(l)/Io(l))

where Ao(l) is the attenuation of the fiber prior to irradiation, L is the length of the irradiated fiber and Iirr, Io are the spectral intensities measured for irradiated and unirradiated cases.

The LIL measurements exhibit the well-known absorption peak of high OH content quartz-fibers around 630 nm. In the range from 400 to 525 nm where the HF detector is sensitive for Cherenkov light, the attenuation is typically varying between 2-3 dB/m. In the results of fast neutron tests the UV-tail and the absorption band at around 630 nm are also clearly observable. At 1E15 n/cm2, the induced loss in the region of interest is about 1 dB/m.

Concerning the R5600 type PMTs we carried out a series of measurements like spectral response, dark current characteristics, gain variation, energy spectroscopy and activation as a function of the neutron flux-rate, fluence and the gamma total dose. We observed no degradation in optical characteristics of the tubes for low-flux and low fluence irradiations.

Id: 78
Corresponding Author: Jean-Pierre Mendiburu
Experiment: CMS
Sub-system: Calorimetry
Topic: Electronics for Calorimeter

An electronic calibration for the readout chain of the ECAL-CMS

Youngwook Baek, Daniel Boget, Pierre Zves Davis, Jean Ditta, Nadia Fouque, Jean Pierre Mendiburu
LAPP Annecy-le-Vieux

Abstract :

A calibration system has been developped in 0.8 µ DMILL technology for ECAL-CMS. It consists of several logic and analogic chips that have been funded, and tested in lab and in irradiation beams.

Summary :

We present the status of the electronic calibration designed for the read-out chain of the CMS-ECAL.

In the LAPP (Annecy, France), we have developed several chips in DMILL 0.8 µ technology to integrate the functionalities dedicated to the electronic calibration. A control chip, receives the signals from outside opto-couplers, it de-serializes and transfers this information to a decoding logical circuit. This one recognizes calibration orders, generates a word  and transfers it to a DAC to select an amplitude or set a trigger to the injector.

The injector builds pulses that have  an amplitude proportional to the order given to the DAC and an exponential decaying shape, identical to the APD’s one. The characteristics of each chip have been measured at LAPP on a chain based on a PC through a Labview program  and VME specific elements. Each chip has been tested under irradiation in running conditions at least up to 1014 neutrons/cm2 and 400 krads in gammas  and proved to be hard at least to 10 years of full LHC luminosity.

Id: 85
Corresponding Author: Dominique BRETON
Experiment: ATLAS
Sub-system: Calorimetry
Topic: Electronics for Calorimeters

HAMAC, a rad-hard high dynamic range analog memory for Atlas calorimetry

E. DELAGNES, P. BORGEAUD
CEA, DSM/DAPNIA SACLAY, 91191 Gif­sur­Yvette, France.

E. AUGE, D. BRETON, G. MARTIN­CHASSARD, V. TOCUT
LABORATOIRE DE L'ACCELERATEUR LINEAIRE, IN2P3­CNRS et Université Paris­Sud, 91405 Orsay Cedex, France.

J. PARSONS, W. SIPPACH
NEVIS LABORATORIES, COLUMBIA UNIVERSITY, IRVINGTON, NY 10533, USA

Abstract:

An 12 channel analog memory dedicated to the readout of the Atlas liquid argon calorimeter has been developed. Its main function is to sample, at a 40 Mhz rate, the data coming from a three gain shaper, to store it, waiting for the level­1 trigger decision, and then to send it more slowly (5MHz) towards a 12 bit ADC. For each trigger, the ADC will digitize 5 samples. As the system is supposed to present minimum dead time, the write operations will be unceasing even during the read phases. The chip can thus be seen as a simultaneous double random access analog memory array. The read and write addresses are generated by a separate controller chip and sent together with other control signals to the analog memory using low­voltage swings.

In the ATLAS calorimetry, the electronics will have to withstand a total ionising dose higher than 20 krad over a 10 year lifetime. For reliability, the circuit may survive to a total dose of 100krad. Thus the chip has been developed in DMILL technology.

The presentation will highlight the amazing level of performance achieved by this circuit whose dynamic range is far in excess of 13 bits even while undergoing simultaneous write and read accesses.