G. Tambave

Pulse pile-up recovery for the front-end electronics of the PANDA electromagnetic calorimeter

To study the Charmonium spectrum and search for narrow exotic hadronic states, predicted by Quantum Chromo-dynamics, the PANDA detector will be employed at the future Facility for Antiproton and Ion Research near Darmstadt in Germany. In the PANDA experiment, 1.5 to 15 GeV/c antiprotons will collide with a hydrogen target at average annihilation rates of 20 MHz. One of the most important sub-detectors of PANDA is the Electromagnetic Calorimeter (EMC) planned for the studies of electromagnetic transitions and neutral meson decays. Due to the high annihilation rates, the EMC will be exposed to single-detector hit rates up to 500 kHz, which may lead to pulse overlap. Hence, to recover the energy and time information of the overlapping pulses, the pulse pile-up recovery method is developed. The method is easy to implement in FPGA for online data processing. The Constant Fraction Timing method is applied at the trailing edge to recover the time stamp of pile-up pulses. The energy of pile-up pulses can be recovered up to time differences equal to the pulse rise-time.

Search for evidence of (3)(Lambda)n by observing d + pi(-) and t + pi(-) final states in the reaction of Li-6+C-12 at 2A GeV

The experimental data obtained from the reaction of Li-6 projectiles at 2A GeV on a fixed graphite target were analyzed to study the invariant mass distributions of d + pi(-) and t + pi(-). Indications of a signal in the d + pi(-) and t + pi(-) invariant mass distributions were observed with significances of 5.3 sigma and 5.0 sigma, respectively, when including the production target, and 3.7 sigma and 5.2 sigma, respectively, when excluding the target. The estimated mean values of the invariant mass for d + pi(-) and t + pi(-) signal were 2059.3 +/- 1.3 +/- 1.7 MeV/c(2) and 2993.7 +/- 1.3 +/- 0.6 MeV/c(2) respectively. The lifetime estimation of the possible bound states yielding to d + pi(-) and t + pi(-) final states were deduced to be as 181(-24)(+30) +/- 25 ps and 190(-35)(+47) +/- 36 ps, respectively. Those final states may be interpreted as the two-body and three-body decay modes of a neutral bound state of two neutrons and a Lambda hyperon, (3)(Lambda)n.

Pulse pile-up recovery for the front-end electronics of the PANDA Electromagnetic Calorimeter

To study the Charmonium spectrum and search for narrow exotic hadronic states, predicted by Quantum Chromo-dynamics, the PANDA detector will be employed at the future Facility for Antiproton and Ion Research near Darmstadt in Germany. In the PANDA experiment, 1.5 to 15 GeV/c antiprotons will collide with a hydrogen target at average annihilation rates of 20 MHz. One of the most important sub-detectors of PANDA is the Electromagnetic Calorimeter (EMC) planned for the studies of electromagnetic transitions and neutral meson decays. Due to the high annihilation rates, the EMC will be exposed to single-detector hit rates up to 500 kHz, which may lead to pulse overlap. Hence, to recover the energy and time information of the overlapping pulses, the pulse pile-up recovery method is developed. The method is easy to implement in FPGA for online data processing. The Constant Fraction Timing method is applied at the trailing edge to recover the time stamp of pile-up pulses. The energy of pile-up pulses can be recovered up to time differences equal to the pulse rise-time.

Performance of Cooled PWO Scintillators With Signal-Sampling Readout

For the investigation of the charmonium spectrum, yet undiscovered charm-meson states and glueballs, the PANDA detector will be employed at the future FAIR facility. PANDA will contain an electromagnetic calorimeter composed of PbWO4 (PWO) crystals that are cooled to -25°C and coupled to large-area avalanche photodiodes or vacuum phototriodes/-tetrodes. The photosensor signals are continuously digitized by sampling analog-to-digital converters (SADCs) and analyzed online in field programmable gate arrays (FPGAs) that are part of the digitizer module to detect hits and extract energy and time information. The online SADC-data processing algorithm was designed, optimized, and implemented in VHDL for a Xilinx FPGA. In order to estimate the performance of the SADC readout of cooled PWO crystals, several measurements with tagged photons in the energy range of 60 MeV-1.4 GeV were performed. The digital readout improves the energy resolution in particular at low photon energies and simultaneously provides a time resolution below 1 ns for an energy deposition above 80 MeV. The successful application of the online data-processing procedure is an essential step toward the development of a trigger-less readout concept of the data acquisition for the PANDA experiment.

Feature-extraction algorithms for the PANDA electromagnetic calorimeter

The feature-extraction algorithms are discussed which have been developed for the digital front-end electronics of the electromagnetic calorimeter of the PANDA detector at the future FAIR facility. Performance parameters have been derived in test measurements with cosmic rays, particle and photon beams.

Search for evidence ofΛ3nby observingd+π−andt+π−final states in the reaction of6Li+12C at2AGeV

The experimental data obtained from the reaction of Li-6 projectiles at 2A GeV on a fixed graphite target were analyzed to study the invariant mass distributions of d + pi(-) and t + pi(-). Indications of a signal in the d + pi(-) and t + pi(-) invariant mass distributions were observed with significances of 5.3 sigma and 5.0 sigma, respectively, when including the production target, and 3.7 sigma and 5.2 sigma, respectively, when excluding the target. The estimated mean values of the invariant mass for d + pi(-) and t + pi(-) signal were 2059.3 +/- 1.3 +/- 1.7 MeV/c(2) and 2993.7 +/- 1.3 +/- 0.6 MeV/c(2) respectively. The lifetime estimation of the possible bound states yielding to d + pi(-) and t + pi(-) final states were deduced to be as 181(-24)(+30) +/- 25 ps and 190(-35)(+47) +/- 36 ps, respectively. Those final states may be interpreted as the two-body and three-body decay modes of a neutral bound state of two neutrons and a Lambda hyperon, (3)(Lambda)n.

Search for evidence of

The experimental data obtained from the reaction of Li-6 projectiles at 2A GeV on a fixed graphite target were analyzed to study the invariant mass distributions of d + pi(-) and t + pi(-). Indications of a signal in the d + pi(-) and t + pi(-) invariant mass distributions were observed with significances of 5.3 sigma and 5.0 sigma, respectively, when including the production target, and 3.7 sigma and 5.2 sigma, respectively, when excluding the target. The estimated mean values of the invariant mass for d + pi(-) and t + pi(-) signal were 2059.3 +/- 1.3 +/- 1.7 MeV/c(2) and 2993.7 +/- 1.3 +/- 0.6 MeV/c(2) respectively. The lifetime estimation of the possible bound states yielding to d + pi(-) and t + pi(-) final states were deduced to be as 181(-24)(+30) +/- 25 ps and 190(-35)(+47) +/- 36 ps, respectively. Those final states may be interpreted as the two-body and three-body decay modes of a neutral bound state of two neutrons and a Lambda hyperon, (3)(Lambda)n.

_{Λ}^{3}n

The PANDA collaboration at FAIR, Germany, will employ antiproton annihilations to investigate yet undiscovered charm-mesons and glueballs aiming to unravel the origin of hadronic masses. A multi-purpose detector for tracking, calorimetry and particle identification is presently being developed to run at high luminosities providing up to 2.107 interactions/s. A trigger-less data-acquisition system will be employed with sub-detectors continuously providing data from incoming physics events. This paper describes readout electronics and the treatment of the digitised preamplifier signal for the Electromagnetic Calorimeter. The use of a Sampling ADC in the readout allows to achieve the design goals, namely a large dynamic range from 1 MeV to 10 GeV, a count-rate dependent low trigger threshold of about 1-3 MeV, and a time resolution better than 1 ns.

by observing

The feature-extraction algorithm, developed for the digital front-end electronics of the electromagnetic calorimeter of the PANDA detector at the future FAIR facility, is implemented in VHDL for a commercial 16 bit 100 MHz sampling ADC. The use of modified firmware with the running on-line data-processing algorithm will allow to perform realistic performance studies of the calorimeter and test a trigger-less readout concept of the data acquisition for the PANDA experiment.