In order to minimize aging effects, the LHCb Muon chambers have to be operated at the lowest poss... more In order to minimize aging effects, the LHCb Muon chambers have to be operated at the lowest possible voltage, and in order to maximize the chamber efficiency, also at the lowest possible threshold. It is therefore crucial to have a good understanding of the noise characteristics of the system. An elegant method has been developed to determine the optimal threshold from noise measurements for each electronics channel. We present first the noise measurements made in laboratory with fully-equipped chambers for threshold optimization. The Gamma Irradiation Facility (GIF) at CERN was used to test the chamber performance under the intense gamma flux, similar to the one expected in the experiment. The results of tests of the various chamber types allow us to conclude that the requirements of the LHCb experiment are achieved.
... L.Alessandrelli, V.Bocci, G.Chiodi, F.Iacoangeli, R.Nobrega, D.Pinci, W.Rinaldi ... ACKNOWLED... more ... L.Alessandrelli, V.Bocci, G.Chiodi, F.Iacoangeli, R.Nobrega, D.Pinci, W.Rinaldi ... ACKNOWLEDGMENTS The authors are deeply indebted to, and would like to thank for their continuous and invaluable help and support Silvano Di Marco, Antonio Rossi, Daniele Ruggeri. ...
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2008
The high-rate performance of a multiwire proportional chamber of the LHCb muon detector was teste... more The high-rate performance of a multiwire proportional chamber of the LHCb muon detector was tested. The chamber, equipped with the final front-end electronics, was tested using a ∼100GeV muon beam superimposed on a 662 keV γγ flux of variable intensity produced by the 137Cs radioactive source of the CERN Gamma Irradiation Facility (GIF). No significant variation in the muon detection efficiency or in the time response of the chamber was observed at the highest gamma rate.
This paper describes the apparatus and the procedures implemented to test the Front-End (FE) elec... more This paper describes the apparatus and the procedures implemented to test the Front-End (FE) electronics of the LHCb Muon Detector Multi Wire Proportional Chambers (MWPC). Aim of the test procedure is to diagnose every FE channel of a given chamber by performing an analysis of the noise rate versus threshold and of the performances at the operational thresholds. Measurements of the key noise parameters, obtained while performing quality tests on the MWPC chambers before the installation on the experiment, are presented. The Test Suite proved to be an automatic, fast and user-friendly system for mass production tests of chambers. It provided the electronic identification of every chamber and FE board, and the storage and bookkeeping of test results that will be made available to the Experiment Control System during data taking.
We have designed and implemented on a Xilinx SpartanIIE FPGA a highly integrated time-multiplexin... more We have designed and implemented on a Xilinx SpartanIIE FPGA a highly integrated time-multiplexing device by means of using multiple fixed delays. Signals coming from MWPCs (multi wire proportional chambers) front end readout circuitry can be multiplexed in time using selected delay values. Up to 5 channels can be merged into one using delays in increments of 150 ns. As a consequence, usage of one multi-hit channel to measure timing of 5 channels is possible. Inside the FPGA a 36 to 8 multiplexing is performed, resulting in a reduction, of more than a factor of four, of the number of multi-hit TDC channels needed.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2011
In a detector with the complexity of the LHCb, where only for the muon system more than 1300 cham... more In a detector with the complexity of the LHCb, where only for the muon system more than 1300 chambers, divided into 20 different types, will be used, resulting on more than 120 k channels to be readout, it is of crucial importance to study the many types of chambers to create a complete knowledge of the detector operation and to guarantee a high-quality performance during the experiment. To make it possible, a complete setup was built and a Cþþ based software was developed to carry out a set of measurements on the full-equipped chambers of the LHCb muon detector. The setup is made of front-end control electronics, high-voltage supply and acquisition circuitry while the software, running on a PC, remotely controls each element of the system and implements a number of automatized procedures to assess the main characteristics of the chambers.
In this note we report the results of performance obtained for the muon detector during this firs... more In this note we report the results of performance obtained for the muon detector during this first year of cosmic rays acquisition of the LHCb experiment. Procedures for optimization of time alignment, threshold setting and noise response have been carried out. Then, the main detector’s characteristics have been tested and studied by means of cosmic rays acquisition in order to
Tracking and position-sensitive detectors Elementary-particle and nuclear physics experimental me... more Tracking and position-sensitive detectors Elementary-particle and nuclear physics experimental methods and instrumentation a b s t r a c t
Background: Spermatogonial stem cells (SSCs) are the foundation of spermatogenesis, and reside wi... more Background: Spermatogonial stem cells (SSCs) are the foundation of spermatogenesis, and reside within a specific microenvironment in the testes called ''niche'' which regulates stem cell properties, such as, self-renewal, pluripotency, quiescence and their ability to differentiate.
Using data collected with the LHCb detector in proton-proton collisions at a centre-ofmass energy... more Using data collected with the LHCb detector in proton-proton collisions at a centre-ofmass energy of 7 TeV, the semileptonic decays B 0 s →
Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energ... more Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays Bs -> Ds+ X mu nu and Bs -> D0 K+ X mu nu are detected. Two structures are observed in the D0 K+ mass spectrum at masses consistent with the known D^+_{s1}(2536) and $D^{*+}_{s2}(2573) mesons. The measured branching fractions relative to the total Bs semileptonic rate are B(Bs -> D_{s2}^{*+} X mu nu)/B(Bs -> X mu nu)= (3.3\pm 1.0\pm 0.4)%, and B(Bs -> D_{s1}^+ X munu)/B(Bs -> X mu nu)= (5.4\pm 1.2\pm 0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D_{s2}^{*+} state in Bs decays; we also measure its mass and width.
The production of K 0 S mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied ... more The production of K 0 S mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The luminosity of the analysed sample is determined using a novel technique, involving measurements of the beam currents, sizes and positions, and is found to be 6.8 ± 1.0 µb −1 . The differential prompt K 0 S production cross-section is measured as a function of the K 0 S transverse momentum and rapidity in the region 0 < p T < 1.6 GeV/c and 2.5 < y < 4.0. The data are found to be in reasonable agreement with previous measurements and generator expectations.
This study aimed to improve, using the zebrafish model, our understanding of the distinct roles o... more This study aimed to improve, using the zebrafish model, our understanding of the distinct roles of pituitary gonadotropins FSH and LH in regulating testis functions in teleost fish. We report, for the first time in a vertebrate species, that zebrafish Leydig cells as well as Sertoli cells express the mRNAs for both gonadotropin receptors (fshr and lhcgr). Although Leydig cell fshr expression has been reported in other piscine species and may be a common feature of teleost fish, Sertoli cell lhcgr expression has not been reported previously and might be related to the undifferentiated gonochoristic mode of gonadal sex differentiation in zebrafish. Both recombinant zebrafish (rzf) gonadotropins (i.e. rzfLH and rzfFSH) stimulated androgen release in vitro and in vivo, with rzfFSH being significantly more potent than rzfLH. Forskolin-induced adenylate cyclase activation mimicked, whereas the protein kinase A inhibitor H-89 significantly reduced, the gonadotropin-stimulated androgen release. Therefore, we conclude that both FSH receptor and LH/choriogonadotropin receptor signaling are predominantly mediated through the cAMP/protein kinase A pathway to promote steroid production. Despite this similarity, other downstream mechanisms seem to differ. For example, rzfFSH up-regulated the testicular mRNA levels of a number of steroidogenesis-related genes both in vitro and in vivo, whereas rzfLH or human chorionic gonadotropin did not. Although not fully understood at present, these differences could explain the capacity of FSH to support both steroidogenesis and spermatogenesis on a long-term basis, whereas LH-stimulated steroidogenesis might be a more acute process, possibly restricted to periods during which peak steroid levels are required. T he pituitary gonadotropins LH and FSH play critical roles in regulating male reproduction across vertebrates (1-3). In mammals, the specific activities of both gonadotropins are clearly defined, given the highly specific interactions between each hormone and its respective receptor, LH/choriogonadotropin receptor (Lhcgr) and FSH receptor (Fshr). In addition, Lhcgr and Fshr expres-sion in mammalian testis is restricted to Leydig and Sertoli cells, respectively (1, 2, 4). Hence, LH predominantly controls Leydig cell steroidogenesis, whereas FSH regulates Sertoli cell functions (2, 4 -6).
The freshwater fish Serrasalmus spilopleura (piranha) has a continuous type of reproduction; game... more The freshwater fish Serrasalmus spilopleura (piranha) has a continuous type of reproduction; gametes are constantly produced and released during the reproductive cycle. The testes do not undergo seasonal morphological changes but exhibit two constant regions throughout the year: the medullar region (involved with spermatogenesis) and the cortical region (involved with spermiation and sperm storage). We have evaluated the ultrastructure of the Leydig cells and the activity of 3β-HSD (an essential enzyme related to steroid hormone biosynthesis) and acid phosphatase (AcPase; lysosomal marker enzyme) in these two regions. The activity of 3β-HSD is stronger in the medullar region, and the Leydig cells in this region have a variety of cytological features that reflect differences in hormone synthesis and/or that could be linked to steroidogenic cells under various degrees of hormonal activity. In the cortical region, 3β-HSD activity is weak and the Leydig cells exhibit signs of degeneration, as confirmed by their ultrastructure and intense AcPase activity. These degenerative signs are indicative of cytoplasmic remodelling to degrade steroidogenic enzymes, such as 3β-HSD, that could lead to senescence or even to autophagic cell degeneration. S. spilopleura thus constitutes an interesting model for increasing our understanding of steroidogenesis control in freshwater teleost fish.
The zebrafish has become an important vertebrate model for basic and biomedical research, includi... more The zebrafish has become an important vertebrate model for basic and biomedical research, including the research field of the biology of reproduction. However, very few morphological and stereological data are available regarding zebrafish testis structure and spermatogenesis. In this careful histomorphometric evaluation of the testis, we studied spermatogonial cells using molecular markers, determined the combined duration of meiotic and spermiogenic phases, and examined the formation of the Sertoli cell barrier (tight junctions). We found at least nine spermatogonial generations and propose a morphology-based nomenclature for spermatogonial generations that is compatible with the one used in higher vertebrates. The number of germ cells per cyst increased dramatically (1 to ;1360 cells) from undifferentiated spermatogonia type A to early spermatids. The combined duration of meiotic and spermiogenic phases is approximately 6 days, one of the shorter periods among the teleost fish investigated to date. The number of Sertoli cells per cyst increased 9-fold during the maturational cycle of spermatogenic cysts and stabilized in the meiotic phase at a ratio of approximately 100 early spermatids per Sertoli cell (Sertoli cell efficiency). Similarly to mammals, Sertoli cell proliferation ceased in the meiotic phase, coinciding with the formation of tight junctions between Sertoli cells. Hence, the events taking place during puberty in the germinal epithelium of mammals seem to recapitulate the ''life history'' of each individual spermatogenic cyst in zebrafish.
In order to minimize aging effects, the LHCb Muon chambers have to be operated at the lowest poss... more In order to minimize aging effects, the LHCb Muon chambers have to be operated at the lowest possible voltage, and in order to maximize the chamber efficiency, also at the lowest possible threshold. It is therefore crucial to have a good understanding of the noise characteristics of the system. An elegant method has been developed to determine the optimal threshold from noise measurements for each electronics channel. We present first the noise measurements made in laboratory with fully-equipped chambers for threshold optimization. The Gamma Irradiation Facility (GIF) at CERN was used to test the chamber performance under the intense gamma flux, similar to the one expected in the experiment. The results of tests of the various chamber types allow us to conclude that the requirements of the LHCb experiment are achieved.
... L.Alessandrelli, V.Bocci, G.Chiodi, F.Iacoangeli, R.Nobrega, D.Pinci, W.Rinaldi ... ACKNOWLED... more ... L.Alessandrelli, V.Bocci, G.Chiodi, F.Iacoangeli, R.Nobrega, D.Pinci, W.Rinaldi ... ACKNOWLEDGMENTS The authors are deeply indebted to, and would like to thank for their continuous and invaluable help and support Silvano Di Marco, Antonio Rossi, Daniele Ruggeri. ...
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2008
The high-rate performance of a multiwire proportional chamber of the LHCb muon detector was teste... more The high-rate performance of a multiwire proportional chamber of the LHCb muon detector was tested. The chamber, equipped with the final front-end electronics, was tested using a ∼100GeV muon beam superimposed on a 662 keV γγ flux of variable intensity produced by the 137Cs radioactive source of the CERN Gamma Irradiation Facility (GIF). No significant variation in the muon detection efficiency or in the time response of the chamber was observed at the highest gamma rate.
This paper describes the apparatus and the procedures implemented to test the Front-End (FE) elec... more This paper describes the apparatus and the procedures implemented to test the Front-End (FE) electronics of the LHCb Muon Detector Multi Wire Proportional Chambers (MWPC). Aim of the test procedure is to diagnose every FE channel of a given chamber by performing an analysis of the noise rate versus threshold and of the performances at the operational thresholds. Measurements of the key noise parameters, obtained while performing quality tests on the MWPC chambers before the installation on the experiment, are presented. The Test Suite proved to be an automatic, fast and user-friendly system for mass production tests of chambers. It provided the electronic identification of every chamber and FE board, and the storage and bookkeeping of test results that will be made available to the Experiment Control System during data taking.
We have designed and implemented on a Xilinx SpartanIIE FPGA a highly integrated time-multiplexin... more We have designed and implemented on a Xilinx SpartanIIE FPGA a highly integrated time-multiplexing device by means of using multiple fixed delays. Signals coming from MWPCs (multi wire proportional chambers) front end readout circuitry can be multiplexed in time using selected delay values. Up to 5 channels can be merged into one using delays in increments of 150 ns. As a consequence, usage of one multi-hit channel to measure timing of 5 channels is possible. Inside the FPGA a 36 to 8 multiplexing is performed, resulting in a reduction, of more than a factor of four, of the number of multi-hit TDC channels needed.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2011
In a detector with the complexity of the LHCb, where only for the muon system more than 1300 cham... more In a detector with the complexity of the LHCb, where only for the muon system more than 1300 chambers, divided into 20 different types, will be used, resulting on more than 120 k channels to be readout, it is of crucial importance to study the many types of chambers to create a complete knowledge of the detector operation and to guarantee a high-quality performance during the experiment. To make it possible, a complete setup was built and a Cþþ based software was developed to carry out a set of measurements on the full-equipped chambers of the LHCb muon detector. The setup is made of front-end control electronics, high-voltage supply and acquisition circuitry while the software, running on a PC, remotely controls each element of the system and implements a number of automatized procedures to assess the main characteristics of the chambers.
In this note we report the results of performance obtained for the muon detector during this firs... more In this note we report the results of performance obtained for the muon detector during this first year of cosmic rays acquisition of the LHCb experiment. Procedures for optimization of time alignment, threshold setting and noise response have been carried out. Then, the main detector’s characteristics have been tested and studied by means of cosmic rays acquisition in order to
Tracking and position-sensitive detectors Elementary-particle and nuclear physics experimental me... more Tracking and position-sensitive detectors Elementary-particle and nuclear physics experimental methods and instrumentation a b s t r a c t
Background: Spermatogonial stem cells (SSCs) are the foundation of spermatogenesis, and reside wi... more Background: Spermatogonial stem cells (SSCs) are the foundation of spermatogenesis, and reside within a specific microenvironment in the testes called ''niche'' which regulates stem cell properties, such as, self-renewal, pluripotency, quiescence and their ability to differentiate.
Using data collected with the LHCb detector in proton-proton collisions at a centre-ofmass energy... more Using data collected with the LHCb detector in proton-proton collisions at a centre-ofmass energy of 7 TeV, the semileptonic decays B 0 s →
Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energ... more Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays Bs -> Ds+ X mu nu and Bs -> D0 K+ X mu nu are detected. Two structures are observed in the D0 K+ mass spectrum at masses consistent with the known D^+_{s1}(2536) and $D^{*+}_{s2}(2573) mesons. The measured branching fractions relative to the total Bs semileptonic rate are B(Bs -> D_{s2}^{*+} X mu nu)/B(Bs -> X mu nu)= (3.3\pm 1.0\pm 0.4)%, and B(Bs -> D_{s1}^+ X munu)/B(Bs -> X mu nu)= (5.4\pm 1.2\pm 0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D_{s2}^{*+} state in Bs decays; we also measure its mass and width.
The production of K 0 S mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied ... more The production of K 0 S mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The luminosity of the analysed sample is determined using a novel technique, involving measurements of the beam currents, sizes and positions, and is found to be 6.8 ± 1.0 µb −1 . The differential prompt K 0 S production cross-section is measured as a function of the K 0 S transverse momentum and rapidity in the region 0 < p T < 1.6 GeV/c and 2.5 < y < 4.0. The data are found to be in reasonable agreement with previous measurements and generator expectations.
This study aimed to improve, using the zebrafish model, our understanding of the distinct roles o... more This study aimed to improve, using the zebrafish model, our understanding of the distinct roles of pituitary gonadotropins FSH and LH in regulating testis functions in teleost fish. We report, for the first time in a vertebrate species, that zebrafish Leydig cells as well as Sertoli cells express the mRNAs for both gonadotropin receptors (fshr and lhcgr). Although Leydig cell fshr expression has been reported in other piscine species and may be a common feature of teleost fish, Sertoli cell lhcgr expression has not been reported previously and might be related to the undifferentiated gonochoristic mode of gonadal sex differentiation in zebrafish. Both recombinant zebrafish (rzf) gonadotropins (i.e. rzfLH and rzfFSH) stimulated androgen release in vitro and in vivo, with rzfFSH being significantly more potent than rzfLH. Forskolin-induced adenylate cyclase activation mimicked, whereas the protein kinase A inhibitor H-89 significantly reduced, the gonadotropin-stimulated androgen release. Therefore, we conclude that both FSH receptor and LH/choriogonadotropin receptor signaling are predominantly mediated through the cAMP/protein kinase A pathway to promote steroid production. Despite this similarity, other downstream mechanisms seem to differ. For example, rzfFSH up-regulated the testicular mRNA levels of a number of steroidogenesis-related genes both in vitro and in vivo, whereas rzfLH or human chorionic gonadotropin did not. Although not fully understood at present, these differences could explain the capacity of FSH to support both steroidogenesis and spermatogenesis on a long-term basis, whereas LH-stimulated steroidogenesis might be a more acute process, possibly restricted to periods during which peak steroid levels are required. T he pituitary gonadotropins LH and FSH play critical roles in regulating male reproduction across vertebrates (1-3). In mammals, the specific activities of both gonadotropins are clearly defined, given the highly specific interactions between each hormone and its respective receptor, LH/choriogonadotropin receptor (Lhcgr) and FSH receptor (Fshr). In addition, Lhcgr and Fshr expres-sion in mammalian testis is restricted to Leydig and Sertoli cells, respectively (1, 2, 4). Hence, LH predominantly controls Leydig cell steroidogenesis, whereas FSH regulates Sertoli cell functions (2, 4 -6).
The freshwater fish Serrasalmus spilopleura (piranha) has a continuous type of reproduction; game... more The freshwater fish Serrasalmus spilopleura (piranha) has a continuous type of reproduction; gametes are constantly produced and released during the reproductive cycle. The testes do not undergo seasonal morphological changes but exhibit two constant regions throughout the year: the medullar region (involved with spermatogenesis) and the cortical region (involved with spermiation and sperm storage). We have evaluated the ultrastructure of the Leydig cells and the activity of 3β-HSD (an essential enzyme related to steroid hormone biosynthesis) and acid phosphatase (AcPase; lysosomal marker enzyme) in these two regions. The activity of 3β-HSD is stronger in the medullar region, and the Leydig cells in this region have a variety of cytological features that reflect differences in hormone synthesis and/or that could be linked to steroidogenic cells under various degrees of hormonal activity. In the cortical region, 3β-HSD activity is weak and the Leydig cells exhibit signs of degeneration, as confirmed by their ultrastructure and intense AcPase activity. These degenerative signs are indicative of cytoplasmic remodelling to degrade steroidogenic enzymes, such as 3β-HSD, that could lead to senescence or even to autophagic cell degeneration. S. spilopleura thus constitutes an interesting model for increasing our understanding of steroidogenesis control in freshwater teleost fish.
The zebrafish has become an important vertebrate model for basic and biomedical research, includi... more The zebrafish has become an important vertebrate model for basic and biomedical research, including the research field of the biology of reproduction. However, very few morphological and stereological data are available regarding zebrafish testis structure and spermatogenesis. In this careful histomorphometric evaluation of the testis, we studied spermatogonial cells using molecular markers, determined the combined duration of meiotic and spermiogenic phases, and examined the formation of the Sertoli cell barrier (tight junctions). We found at least nine spermatogonial generations and propose a morphology-based nomenclature for spermatogonial generations that is compatible with the one used in higher vertebrates. The number of germ cells per cyst increased dramatically (1 to ;1360 cells) from undifferentiated spermatogonia type A to early spermatids. The combined duration of meiotic and spermiogenic phases is approximately 6 days, one of the shorter periods among the teleost fish investigated to date. The number of Sertoli cells per cyst increased 9-fold during the maturational cycle of spermatogenic cysts and stabilized in the meiotic phase at a ratio of approximately 100 early spermatids per Sertoli cell (Sertoli cell efficiency). Similarly to mammals, Sertoli cell proliferation ceased in the meiotic phase, coinciding with the formation of tight junctions between Sertoli cells. Hence, the events taking place during puberty in the germinal epithelium of mammals seem to recapitulate the ''life history'' of each individual spermatogenic cyst in zebrafish.
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Papers by Rafael Nobrega