Identification Detector Research Articles

Experience from the construction and installation of the HMPID CsI-RICH detector in ALICE

The construction and installation phases of the High Momentum Particle IDentification (HMPID) detector of the ALICE experiment were completed by summer 2006. The total active area of the detector is 11 m 2 . It represents the largest scale application of CsI photo-cathodes in RICH detectors to date. We will report on the production of the CsI photo-cathodes, the readout electronics, the Multi-wire Proportional Chambers (MWPCs) and the assembly and handling procedures needed to produce such a large detector.

Improvement of Mass Resolution for Iron Isotopes in CR-39 Track Detector

The capability of the CR-39 track detector for isotope identification was verified using 56Fe and 55Fe beams from the heavy ion accelerator HIMAC at NIRS. A CR-39 stack was exposed to 56Fe and 55Fe beams with the energies of 460 MeV/nucleon. Drastic improvements in the accuracies of microscopic image analysis and detector thickness measurement enabled us to identify those iron isotopes with high mass resolution using the CR-39 track detector. As a consequence of the reduction of systematic errors, the mass resolution for iron isotopes in the CR-39 detector was obtained to be 0.22±0.03 amu in rms. The mass resolution newly obtained by the CR-39 detector was compared with the former result and found to be 66% better than the former value of mass resolution as a result of reducing the systematic errors of mass dispersion. Moreover, the ultimate mass resolution of the CR-39 detector was estimated by calculation using those experimental results. As a consequence of reducing the random error, it is expected that the mass resolution for iron isotopes can ultimately approach to ∼0.10 amu in the CR-39 detector.

Construction and expected performance of the hadron blind detector for the PHENIX experiment at RHIC

A new hadron blind detector (HBD) for electron identification in high density hadron environment has been installed in the PHENIX experiment at RHIC in the fall of 2006. The HBD will identify low momentum electron–positron pairs to reduce the combinatorial background in the e+e− mass spectrum, mainly in the region below 1 GeV/c2. The HBD is a windowless proximity-focusing Cherenkov detector with a radiator length of 50 cm, a CsI photocathode and three layers of gas electron multipliers (GEM). Pure CF4 is used as a radiator and a detector gas. This proceeding describes the construction details and the expected performance of the HBD.

Visualisation of liposomes prepared from skin and stratum corneum lipids by transmission electron microscopy

Transmission electron microscopy was used to visualize the liposomes prepared from total lipids extracted from mouse, human and porcine skin and stratum corneum. The total lipid composition was monitored by high precision thin layer chromatography coupled with a flame identification detector (HPTLC/FID, Iatroscan) and the fatty acid content of the samples was monitored by gas chromatography. The liposomes were prepared by the thin lipid film hydration method and they were visualized by transmission electron microscopy after negative staining using uranyl acetate. The structure of the vesicular structures present in the formulations largely depended on the lipid composition of the samples. The liposomes with high ceramide content were drop like vesicles with sharp tips, whereas the presence of excessive phospholipid content lead to bag like liposomes with two hemispheres divided by a membrane. Finally, the tendency of triacylglycerides to accumulate in the lipophylic region of the lipid bilayer, forms membranes with uneven thickness, resulting in structures with undulated membranes. A degree of fusion depending on the phospholipid content was also observed.

The current progress of the ALICE Ring Imaging Cherenkov Detector

Recently, the last two modules (out of seven) of the ALICE High Momentum Particle Identification Detector (HMPID) were assembled and tested. The full detector, after a pre-commissioning phase, has been installed in the experimental area, inside the ALICE solenoid, at the end of September 2006. In this paper, we review the status of the ALICE/HMPID project and we present a summary of the series production of the CsI photo-cathodes. We describe the key features of the production procedure which ensures high-quality photo-cathodes as well as the results of the quality assessment performed by means of a specially developed 2D scanner system able to produce a detailed map of the CsI photo-current over the entire photo-cathode surface. Finally, we present our recent R&D efforts toward the development of a novel generation of imaging Cherenkov detectors with the aim to identify, in heavy-ion collisions, hadrons up to 30 GeV/ c.

Future charged kaon decay experiments

Future experiments aiming to perform precise measurement of rare kaon decays are briefly reviewed; in particular those experimental programs designed to gain new insight on the Unitarity triangle and on the CKM mechanism by observing an hundred of events of the K + → π + ν ν ¯ decay are considered. This rare process, BR ∼ 10 −10 , is computed with very small theoretical errors, providing one of the cleanest tests of the Standard Model (SM) and, possibly, it could give some hints on the flavour structure of New Physics. A target accuracy of order 10% should be reached, thus making experiments in this field very challenging projects, expecially with respect to backgrounds suppression, particle identification capabilities and detector efficiency, while keeping costs and complexity at a reasonable level.

Study of gas Cherenkov detectors for high momentum charged particle identification

We present here an exhaustive study of the possibilities offered by a combination of a gas radiator of the highest index of refraction commercially available ( C 5 F 12 ) with the proven concept of large area CsI photocathodes instrumenting either a multiwire chamber or a GEM detector. We will present two geometries. One of them is proximity-focusing, nevertheless allows identification in a large momentum range. The second geometry deals with the possibilities of using focusing with a spherical mirror. Simulations of the performance are presented.

A 30 ps timing resolution for single photons with multi-pixel Burle MCP-PMT

We have achieved ∼30 ps single-photoelectron and ∼9.1 ps for multi-photoelectron timing resolution with a new 64-pixel Burle MCP-PMT with 10 μm microchannel holes. We have also demonstrated that this detector works in a magnetic field of 15 kG, and achieved a single-photoelectron timing resolution of better than 60 ps The study is relevant for a new focusing DIRC RICH detector for particle identification at future colliders such as the super B-factory or ILC, and for future TOF techniques. This study shows that a highly pixilated MCP-PMT can deliver excellent timing resolution.

Profiling of phenolic glycosidic conjugates in leaves of Arabidopsis thaliana using LC/MS

Profiling of plant secondary metabolites is still a very difficult task. Liquid chromatography (LC) or capillary electrophoresis hyphenated with different kinds of detectors are methods of choice for analysis of polar, thermo labile compounds with high molecular masses. We demonstrate the applicability of LC combined with UV diode array or/and mass spectrometric detectors for the unambiguous identification and quantification of flavonoid conjugates isolated from Arabidopsis thaliana leaves of different genotypes and grown in different environmental conditions. During LC/UV/MS/MS analyses we were able to identify tetra-, tri-, and di-glycosides of kaempferol, quercetin and isorhamnetin. Based on our results we can conclude that due to the co-elution of different chemical compounds in reversed phase HPLC systems the application of UV detectors does not allow to precisely profile all flavonoid conjugates existing in A. thaliana genotypes. Using MS detection it was possible to unambiguously recognize the glycosylation patterns of the aglycones. However, from the mass spectra we could not conclude neither the anomeric form of the C-1 carbon atoms of sugar moieties in glycosidic bonds between sugars or sugar and aglycone nor the position of the second carbon involved in disaccharides. The applicability of collision induced dissociation techniques (CID MS/MS) for structural analyses of the studied group of plant secondary metabolites with two types of analyzers (triple quadrupole or ion trap) was demonstrated.

Microelectrical noise detector for rapid, specific, and sensitive identification of bacteria

Recently, sensing of phase-triggered ion cascades (SEPTIC), a nanotechnology for rapid detection of live, pathogenic bacteria on the scale of minutes with unparalleled specificity, has drawn a lot of attention. SEPTIC utilizes a nanowell device, consisting of two metal electrodes with a gap between 5 and 200nm, to probe the ion effluxes from specific bacteria when they are infected by phages. Whether the effluxes occur can be identified by evaluating the power spectral density of the voltage noise in the nanowell. This article presents further development of SEPTIC, using E. coli, E. coli phage T7, and a control bacteria as analytes. A microwell, identical to a nanowell except that the gap is 4μm, proved capable of probing the ion efflux as well. When ion efflux occurred, abnormal pulses that were much higher than the noise level and lasted for 0.1–0.3s were observed in the voltage noise output from the microwell. These durations agree with the average duration of ion efflux. While in negative tests, observed abnormal pulses were much shorter than 0.1s. Also, positives showed 1∕f noise while negatives showed white noise in 1–10Hz. No false positives or negatives were observed. Given the size of microwell and the simplified detection electronics, the cost of SEPTIC is significantly reduced and the robustness is well improved, indicating very promising applications in clinical diagnosis and biodefense.

The front-end electronics of the LHCb ring-imaging-Cherenkov system

The LHCb experiment at the CERN Large Hadron Collider will use ring-imaging Cherenkov detectors for particle identification. By measuring rings of Cherenkov photons generated by elementary particles traversing a radiative medium, these particles can be identified across a wide range of momenta. The photons will be measured by a new type of detector, the pixel hybrid photon detector (HPD). In total, 484 HPDs will be used, providing ∼500,000 channels of data. Specific readout electronics have been developed for processing the data from the HPDs, and this paper describes the design and testing of these devices together with the final system to be used in the experiment. Emphasis is on the application-specific integrated circuits that are encapsulated within the HPDs, allowing high channel density and low noise. These are subject to the strict requirements of efficient photon detection and reliability within the harsh environment of the experiment. Special interconnect techniques developed for this application are described. Finally, the additional electronics infrastructure to readout the full system of 500,000 channels is outlined, including data transmission and power distribution.

PAMELA SCIENCE

The PAMELA satellite-borne experiment1, to be launched in 2005, is a powerful spectrometer including a magnetic field tracker and particle identification detectors. PAMELA science is broad and includes studies of interstellar propagation, solar modulation and search for dark matter signals.

High-resolution Compton-suppressed CZT and LaCl/sub 3/ detectors for fission products identification

Room-temperature semiconductor CdZnTe (CZT) detectors are currently limited to total detector volumes of 1-2 cm/sup 3/, which is dictated by poor charge transport characteristics. Because of this size limitation, one of the problems in accurately determining isotope identification is the enormous background from Compton scattering events. Eliminating this background will not only increase the sensitivity and accuracy of measurements, but will also help to resolve peaks buried under the background and peaks in close vicinity to others. We are currently developing a fission products detection system based on Compton-suppressed CZT and LaCl/sub 3/ (Ce) detectors. In this application, the detection system is required to operate in a high radiation field. Therefore, a small 10 mm /spl times/10 mm/spl times/5 mm CZT and 13mm/spl times/15mm LaCl/sub 3/ detector are placed inside the center of a well-shielded 76 mm by 76 mm long NaI detector. So far, we have been able to successfully reduce Compton background by a factor of 3.7 to 4.0 for a /sup 137/Cs spectrum. In this work, we will discuss the performance of this detection system using both CZT and LaCl/sub 3/ detectors. The results are compared with MCNP calculations.

Development of ANN-based virtual fault detector for Wheatstone bridge-oriented transducers

This paper reports on the development of a new artificial neural network-based virtual fault detector (VFD) for detection and identification of faults in DAS-connected Wheatstone bridge-oriented transducers of a computer-based measurement system. Experimental results show that the implemented VFD is convenient for fusing intelligence into such systems in a user-interactive manner. The performance of the proposed VFD is examined experimentally to detect seven frequently occurring faults automatically in such transducers. The presented technique used an artificial neural network-based two-class pattern classification network with hard-limit perceptrons to fulfill the function of an efficient residual generator component of the proposed VFD. The proposed soft residual generator detects and identifies various transducer faults in collaboration with a virtual instrument software-based inbuilt algorithm. An example application is also presented to demonstrate the use of implemented VFD practically for detecting and diagnosing faults in a pressure transducer having semiconductor strain gauges connected in a Wheatstone bridge configuration. The results obtained in the example application with this strategy are promising.

Development of photon detectors for a fast focusing DIRC

We report progress in developing a focusing DIRC with very good timing resolution. This basic detector development has been motivated by a possible upgrade of the very successful BaBar DIRC particle identification detector for a future Super B-factory. We have built a single bar full size prototype, which aims to reduce the chromatic error by precise timing, and to remove the effect of bar thickness with a focusing mirror. This paper describes the design of the prototype, and systematic studies of the timing resolution and position response for single photons for two 64-pixel detectors: (a) Hamamatsu Flat Panel PMTs, and (b) Burle MCP–PMTs. To test the prototype, we have developed new electronics for ∼300 pixels capable of measuring a single electron timing resolution to ∼100 ps. We also report on a first measurement of aging with the MCP–PMT.

Identification and Quantification of 8 Sulfonylureas with Clinical Toxicology Interest by Liquid Chromatography–Ion-Trap Tandem Mass Spectrometry and Library Searching

Identification of sulfonylureas in blood may be useful in the evaluation of hypoglycemic crises of unknown origin. The aim of the present study was to develop a highly selective liquid chromatography-electrospray tandem mass spectrometry (MS-MS) method using an ion-trap detector for rapid screening, identification, and quantification of sulfonylureas in human plasma. After standard liquid-liquid extraction with glisoxepide as an internal standard, 8 sulfonylureas (glibenclamide, glipizide, gliclazide, glibornuride, glimepiride, carbutamide, chlorpropamide, and tolbutamide) were eluted from a C18 column within 10 min with an isocratic mobile phase. Drugs were identified and quantified in full-scan MS-MS mode by use of a homemade MS-MS library. We used the assay in 134 cases of hypoglycemic crises of unknown origin. No ion suppression effect was noted for the analytes at their specific retention-time windows. For all drugs, assay validation showed good linearity (r2>0.990) and acceptable imprecision and recovery based on commonly used criteria of acceptance. The mean extraction recoveries were 63%-87% for 5 sulfonylureas but <45% for 3 (carbutamide, chlorpropamide, and tolbutamide). Nevertheless, the high sensitivity of the MS instrument made possible detection and quantification of all 8 drugs at subtherapeutic to toxic concentrations with good precision. Sulfonylureas were found in 9 hypoglycemic patients. The described assay method allows accurate, rapid identification and quantification of 8 sulfonylureas in human plasma and can be used for specific diagnosis of factitious hypoglycemia caused by ingestion of these drugs.

Performance of the high momentum particle identification CsI-RICH for ALICE at CERN-LHC

The ALICE High Momentum Particle Identification (HMPID) detector consists of an array of seven identical proximity focusing Ring Imaging Cherenkov counters. It has been designed to identify charged pions and kaons in the range 1 < p t < 3 GeV / c and protons in the range 2 < p t < 5 GeV / c . The total active area of this detector is about 11 m 2 and represents the largest scale application of CsI photocathodes to date. The detector performance, as being evaluated in test beam at CERN, will be discussed for the first five modules.

Use of a single crystal diffractometer and CCD area detector for phase identification

Use of a single crystal diffractometer and CCD area detector for phase identification

Screening for anthocyanins using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry with precursor-ion analysis, product-ion analysis, common-neutral-loss analysis, and selected reaction monitoring

A systematic method for anthocyanin identification using tandems mass spectrometry (MS/MS) coupled to high-performance liquid chromatography (HPLC) with photo-diode array detection (PDA) was developed. Scan for the precursor ions of commonly found anthocyanidins (cyanidin, delphinidin, malvidin, pelargonidin, petunidin, and peonidin) using LC/MS/MS on a triple quadrupole instrument allows for the specific determination of each category of anthocyanins. Further characterization of each anthocyanin was performed using MS/MS product-ion analysis, common-neutral-loss analysis, and selected reaction monitoring (SRM). The method was demonstrated for analysis of anthocyanins in black raspberries, red raspberries, highbush blueberries, and grapes ( Vitis vinifera). Previous reported anthocyanins in black raspberries and red raspberries are confirmed and characterized. Common-neutral-loss analysis allows for the distinction of anthocyanin glucosides or galactoside and arabinosides in highbush blueberries. Separation and identification of anthocyanin glucosides and galactosides were achieved by LC/MS/MS using SRM. Anthocyanin isomers such as cyanidin sophoroside and 3,5-diglucoside were differentiated by their fragmentation pattern during product-ion analysis. Fifteen anthocyanins (all possible combinations of five anthocyanidins and three sugars) were characterized in highbush blueberries. Pelargonidin 3-glucoside and pelargonidin 3,5-diglucoside were detected and characterized for the first time in grapes. The present approach allows mass spectrometry to be used as a highly selective detector for rapid identification and characterization of anthocyanins and can be used as a sensitive procedure for screening anthocyanins in fruits and vegetables.

Status of the HMPID CsI-RICH project for ALICE at the CERN/LHC

The ALICE (A Large Ion Collider Experiment) high momentum particle identification (HMPID) detector, presently under construction, consists of seven identical proximity focusing ring imaging Cherenkov (RICH) counters exploiting large area CsI photocathodes for Cherenkov light imaging. With a total area of 11 m/sup 2/, it represents the largest CsI-RICH system ever used in High Energy Physics. The detector layout, assembly and quality checks will be presented, with particular emphasis on CsI photocathodes mass production. A validation procedure has been established combining the results of the photocathode response mapping obtained in a dedicated VUV scanner with test beam data. The long-term stability has also been studied by irradiation with a Sr-90 source of a final size CsI photocathode inside a detector prototype.