ICALEPCS2011 - List of Authors (Rey, F.)

Paper

Title

Page

A New Fast Triggerless Acquisition System For Large Detector Arrays

935

P. Mutti, M. Jentschel, J. Ratel, F. Rey, E. Ruiz-Martinez, W. Urban
ILL, Grenoble, France

Presently a common characteristic trend in low and medium energy nuclear physics is to develop more complex detector systems to form multi-detector arrays. The main objective of such an elaborated set-up is to obtain comprehensive information about the products of all reactions. State-of-art γ-ray spectroscopy requires nowadays the use of large arrays of HPGe detectors often coupled with anti-Compton active shielding to reduce the ambient background. In view of this complexity, the front-end electronics must provide precise information about energy, time and possibly pulse shape. The large multiplicity of the detection system requires the capability to process the multitude of signals from many detectors, fast processing and very high throughput of more that 10⁶ data words/sec. The possibility to handle such a complex system using traditional analogue electronics has shown rapidly its limitation due, first of all, to the non negligible cost per channel and, moreover, to the signal degradation associated to complex analogue path. Nowadays, digital pulse processing systems are available, with performances, in terms of timing and energy resolution, equal when not better than the corresponding analogue ones for a fraction of the cost per channel. The presented system uses a combination of a 15-bit 100 MS/s digitizer with a PowerPC-based VME single board computer. Real-time processing algorithms have been developed to handle total event rates of more than 1 MHz, providing on-line display for single and coincidence events.

Poster WEPMN025 [15.172 MB]

WEPMS016

Network on Chip Master Control Board for Neutron's Acquisition

1006

E. Ruiz-Martinez, T. Mary, P. Mutti, J. Ratel, F. Rey
ILL, Grenoble, France

In the neutron scattering instruments at the Institute Laue-Langevin, one of the main challenges for the acquisition control is to generate the suitable signalling for the different modes of neutron acquisition. An inappropriate management could cause loss of information during the course of the experiments and in the subsequent data analysis. It is necessary to define a central element to provide synchronization to the rest of the units. The backbone of the proposed acquisition control system is the denominated master acquisition board. This main board is designed to gather together the modes of neutron acquisition used in the facility, and make it common for all the instruments in a simple, modular and open way, giving the possibility of adding new performances. The complete system also includes a display board and n histogramming modules connected to the neutrons detectors. The master board consists of a VME64X configurable high density I/O connection carrier board based on latest Xilinx Virtex-6T FPGA. The internal architecture of the FPGA is designed as a Network on Chip (NoC) approach. It represents a switch able to communicate efficiently the several resources available in the board (PCI Express, VME64x Master/Slave, DDR3 controllers and user's area). The core of the global signal synchronization is fully implemented in the FPGA, the board has a completely user configurable IO front-end to collect external signals, to process them and to distribute the synchronization control via the bus VME to the others modules involved in the acquisition.

Poster WEPMS016 [7.974 MB]

WEPMS019

Measuring Angle with Pico Meter Resolution

1014

P. Mutti, M. Jentschel, T. Mary, F. Rey
ILL, Grenoble, France
G. Mana, E. Massa
INRIM, Turin, Italy

The kilogram is the only remaining fundamental unit within the SI system that is defined in terms of a material artefact (a PtIr cylinder kept in Paris). Therefore, one of the major tasks of modern metrology is the redefinition of the kilogram on the basis of a natural quantity or of a fundamental constant. However, any kilogram redefinition must approach a 10^-8 relative accuracy in its practical realization. A joint research project amongst the major metrology institutes in Europe has proposed the redefinition of the kilogram based on the mass of the ¹²C atom. The goal can be achieved by counting in a first step the number of atoms in a macroscopic weighable object and, in a second step, by weighing the atom by means of measuring its Compton frequency vC. It is in the second step of the procedure, where the ILL is playing a fundamental role with GAMS, the high-resolution γ-ray spectrometer. Energies of the γ-rays emitted in the decay of the capture state to the ground state of a daughter nucleus after a neutron capture reaction can be measured with high precision. In order to match the high demand in angle measurement accuracy, a new optical interferometer with 10 picorad resolution and linearity over a total measurement range of 15° and high stability of about 0.1 nrad/hour has been developed. To drive the interferometer, a new FPGA based electronics for the heterodyne frequency generation and for real time phase measurement and axis control has been realized. The basic concepts of the FPGA implementation will be revised.

Poster WEPMS019 [6.051 MB]

Paper	Title	Page
WEPMN025	A New Fast Triggerless Acquisition System For Large Detector Arrays	935
	P. Mutti, M. Jentschel, J. Ratel, F. Rey, E. Ruiz-Martinez, W. Urban ILL, Grenoble, France
	Presently a common characteristic trend in low and medium energy nuclear physics is to develop more complex detector systems to form multi-detector arrays. The main objective of such an elaborated set-up is to obtain comprehensive information about the products of all reactions. State-of-art γ-ray spectroscopy requires nowadays the use of large arrays of HPGe detectors often coupled with anti-Compton active shielding to reduce the ambient background. In view of this complexity, the front-end electronics must provide precise information about energy, time and possibly pulse shape. The large multiplicity of the detection system requires the capability to process the multitude of signals from many detectors, fast processing and very high throughput of more that 10⁶ data words/sec. The possibility to handle such a complex system using traditional analogue electronics has shown rapidly its limitation due, first of all, to the non negligible cost per channel and, moreover, to the signal degradation associated to complex analogue path. Nowadays, digital pulse processing systems are available, with performances, in terms of timing and energy resolution, equal when not better than the corresponding analogue ones for a fraction of the cost per channel. The presented system uses a combination of a 15-bit 100 MS/s digitizer with a PowerPC-based VME single board computer. Real-time processing algorithms have been developed to handle total event rates of more than 1 MHz, providing on-line display for single and coincidence events.
	Poster WEPMN025 [15.172 MB]

WEPMS016	Network on Chip Master Control Board for Neutron's Acquisition	1006
	E. Ruiz-Martinez, T. Mary, P. Mutti, J. Ratel, F. Rey ILL, Grenoble, France
	In the neutron scattering instruments at the Institute Laue-Langevin, one of the main challenges for the acquisition control is to generate the suitable signalling for the different modes of neutron acquisition. An inappropriate management could cause loss of information during the course of the experiments and in the subsequent data analysis. It is necessary to define a central element to provide synchronization to the rest of the units. The backbone of the proposed acquisition control system is the denominated master acquisition board. This main board is designed to gather together the modes of neutron acquisition used in the facility, and make it common for all the instruments in a simple, modular and open way, giving the possibility of adding new performances. The complete system also includes a display board and n histogramming modules connected to the neutrons detectors. The master board consists of a VME64X configurable high density I/O connection carrier board based on latest Xilinx Virtex-6T FPGA. The internal architecture of the FPGA is designed as a Network on Chip (NoC) approach. It represents a switch able to communicate efficiently the several resources available in the board (PCI Express, VME64x Master/Slave, DDR3 controllers and user's area). The core of the global signal synchronization is fully implemented in the FPGA, the board has a completely user configurable IO front-end to collect external signals, to process them and to distribute the synchronization control via the bus VME to the others modules involved in the acquisition.
	Poster WEPMS016 [7.974 MB]

WEPMS019	Measuring Angle with Pico Meter Resolution	1014
	P. Mutti, M. Jentschel, T. Mary, F. Rey ILL, Grenoble, France G. Mana, E. Massa INRIM, Turin, Italy
	The kilogram is the only remaining fundamental unit within the SI system that is defined in terms of a material artefact (a PtIr cylinder kept in Paris). Therefore, one of the major tasks of modern metrology is the redefinition of the kilogram on the basis of a natural quantity or of a fundamental constant. However, any kilogram redefinition must approach a 10^-8 relative accuracy in its practical realization. A joint research project amongst the major metrology institutes in Europe has proposed the redefinition of the kilogram based on the mass of the ¹²C atom. The goal can be achieved by counting in a first step the number of atoms in a macroscopic weighable object and, in a second step, by weighing the atom by means of measuring its Compton frequency vC. It is in the second step of the procedure, where the ILL is playing a fundamental role with GAMS, the high-resolution γ-ray spectrometer. Energies of the γ-rays emitted in the decay of the capture state to the ground state of a daughter nucleus after a neutron capture reaction can be measured with high precision. In order to match the high demand in angle measurement accuracy, a new optical interferometer with 10 picorad resolution and linearity over a total measurement range of 15° and high stability of about 0.1 nrad/hour has been developed. To drive the interferometer, a new FPGA based electronics for the heterodyne frequency generation and for real time phase measurement and axis control has been realized. The basic concepts of the FPGA implementation will be revised.
	Poster WEPMS019 [6.051 MB]