BLM System Research Articles

Detector design and performance tests of the ESS-neutron Beam Loss Monitor detectors

A new type of beam loss monitor has been developed based on the detection of fast neutrons produced by beam losses in hadron linear accelerators. This neutron sensitive Beam Loss Monitor (nBLM) has been concieved to fulfil the requirements of the European Spallation Source (ESS) and it will be part of the ESS neutron sensitive BLM system (ESS-nBLM). It has been specifically designed for the low energy part, where only neutrons and gammas produced by the loss can exit the accelerator vessel. Here other types of BLM, based on charged particle detection, suffer from the lack of signal compared to the photon background induced by the radio-frequency cavities. However, it can also be operated in regions of higher energy. The detector is of the Micromegas type and have been designed at IRFU to be able to detect fast neutrons while having a small sensitivity to gammas and thermal neutrons. In this work we focus on the proof of neutron-to-gamma rejection and the first operation of the detector in real beam conditions during the commissioning of LINAC4 (CERN). Controlled beam losses were provoked and have been detected by the nBLM detector installed, demonstrating also the discrimination of the neutron signal from RF x-ray background.

The effect of Triton X surfactants on Pb (II) transport rate using bulk liquid membrane systems

Implementation of the "bulk liquid membrane" (BLM) system was investigated in terms of its efficiency for selective removal of heavy metal ions from natural resources and industrial wastewater. In this paper, the removal of lead (II) ions through a liquid membrane system and factors that influence the process were examined. The research was performed using the homemade transport cell. Two organic solvents were used as liquid membranes: 1,2-dichloroethane and chloroform. Metal ion concentration in aqueous phases was monitored by flame atomic absorption spectrophotometry, after 4 hours of experiment. Macrocyclic ether (dicyclohexano-18-crown-6) was used as ligand for Pb (II) ions. The effects of nonionic surfactants (Triton X-100, Triton X-45 and Triton X-405) added in the receiving phase of BLM system were investigated. The results showed significant increase in transport rate compared to systems without surfactants. Considering the surfactant structure, transport rate of Pb (II) ions followed the order: TX-100 >TX-45>TX-405. Presence of TX-100 increased transport of Pb (II) ions up to 78% through chloroform and 58% through 1,2-dichloroethane. Â

Extraction and carrier mediated transport of urea using noncyclic receptors through liquid membrane systems

Extraction and carrier mediated transport through bulk liquid membrane and supported liquid membrane systems have wide applications in separation technology. This paper highlights the use of six noncyclic receptors (podands) having variations in chain length and end group for the removal of urea using liquid membrane system. These receptors R1, R2, R3, R4, R5, R6 are diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, diethylene glycol dibenzoate, diethylene glycol, triethylene glycol and tetraethylene glycol respectively. The sequence of extraction and transport of urea by BLM system using various receptors is R2 > R3 > R1 > R4 > R5 > R6 and R6 ≈ R3 > R5 > R4 > R1 > R2 respectively. Receptor R2 containing butyl end group is best extractant while receptor R6 with flexible backbone is best carrier and this carrier efficiency is used to remove urea using BLM system from the feed phase by recyclization process up to 88.16%. The experimental results influenced by concentration of receptors and urea. Effect of time was also studied.

Embedded EPICS based beam loss monitor system of HLS-II storage ring

A new beam loss monitor system based on embedded EPICS is developed for the top-off upgrade of HLS-Ⅱ, to monitor the position and value of beam loss of storage ring. The electron shower signals are obtained by the double PIN photodiode detectors around the storage ring, then acquired by the new BLM processors, where the beam loss signals are analysed and distributed to the accelerator control network, by embedded EPICS on embedded Linux system of the BLM processors, and the beam loss data could be obtained in the central control room. The new BLM system could actuate the self-checking function of the double PIN photodiode detectors, eliminate hidden malfunction of the detectors, and improve stability and reliability of the whole system. Preliminary operation shows that the new BLM system can meet the needs of the top-off upgrade of HLS-Ⅱ.

Study on the selection of BLM detector for C-ADS Injector II

The injector of C-ADS (Chinese Accelerator Driven Sub-critical System) project is a high current, fully super-conducting proton accelerator. Meanwhile, a BLM system is indispensable for this facility, especially in low energy segments. This paper presents some basic simulations for 10 MeV proton by Monte Carlo program FLUKA, as well as the distributions on different secondary particles in three aspects: angular, energy spectrum, and current. These results are beneficial to selecting the detector type and its location and determining its dynamic range matching different requirements for both fast and slow beam loss. Furthermore, in this paper the major impact of the background is also analyzed, such as superconducting cavity X radiation and radiation caused by material activation. This work is meaningful in BLM system research.

Voltammetric study of charge transfer across supported bilayer lipid membranes (s-BLMs)

Stable bilayer lipid membranes on a metal support (s-BLMs) and on an agar gel salt bridge (sb-BLMs) have been formed and their potential usefulness as practical sensors demonstrated. This paper presents the preparation method of s-BLMs and sb-BLMs, and the application of cyclic voltammetry (CV) to their investigation. The instrument and data analysis of the CV are described. The application of CV to the C 60-doped BLM system is presented. This technique is a basis for biosensor development, and a useful tool for membrane research.

Electrochemical studies of lipophilic ion transport through BLM. The influence of sterols on its transport

AbstractCyclic voltammetry was employed to study the influence of sterols on the lipophilic ion transport through the BLM. The mole fraction of the sterols (cholesterol, oxidized cholesterol), as referred to total lipid, was varied in a range of 0–0.8. Data demonstrate that a thin‐layer model is suitable to this BLM system, By this model, the number of charges transported per lipophilic ion, the concentration of the ion in the membrane hulk phase and the aqueous/membrane phase partition coefficient could be calculated. These parameters proved that sterols had an obvious influence on the lipophilic ion transport. Cholesterol had a stronger influence on the ion transport than oxidized cholesterol. Its incorporation into egg lecithin membranes increased the partition coefficientβ of the ion up to more than 3‐fold. Yet, oxidized cholesterol incorporated into egg lecithin membranes only increased the β up to less than 2‐fold, and the β had no great variation at different oxidized cholesterol mole fractions. The higher β obtained was partly due to the trace amount of solvent existing in the core of the lipid bilayers. At the different sterol mole fractions, combining the change of β with the change of peak current, we also concluded that sterols had somewhat inhibiting effect on the ion transport at the higher sterols mole fraction (> 0.4). These results are explained in terms of the possible change of dipole potential of the membrane produced by sterols and the decrease of the membrane fluidity caused by the condensation effect of sterols and the thinning effect caused by sterols. The substituting group (in the oxidized cholesterol) had some inhibiting effects on the ion transport at higher mole fractions (oxidized cholesterol mole fraction > 0.4).

Immobilization of Ferrocene on a BLM System: An Amperometric Sensor of Fe(CN)6−3/−4Ions

Abstract The redox reactions for a solid supported BLM electrode containing vinyl-ferrocene as an electron mediator in glyceryldioleate dissolved in squalene with a Teflon coated wire (Pt or SS) as a solid support have been investigated using cyclic voltammetry. The results have shown that (i) ferrocene can be very easily immobilized on the surface of a metallic electrode by the new supported BLM (s-BLM) system. This demonstrates that the s-BLM system offers a novel approach to the electrode modification by simple way of immobilization of compounds within BLM, and (ii) ferrocene in a bilayer lipid membrane increases about two orders of magnitude a potassium cyanide ion sensitivity of the platinum electrode.

Lead ion sensitive electrode based on a supported BLM system

The lead ion sensitivity of a solid-supported BLM system containing TCNQ (7, 7, 8, 8-tetracy-anoquinodimethan) as an electron mediator in 4, 4′-n-octyl-cyanobiphenyl (8CB) dissolved in squalene, with a teflon coated platinum wire as a solid support, has been investigated with cyclic voltammetry. The results have shown that TCNQ in a cyanobiphenyl bilayer membrane produces a unique System that increases by three orders of magnitude the lead ion sensitivity of the platinum electrode. Cyclic voltammograms have also shown that a charge-transfer complex between liquid crystal and TCNQ molecules is created and participates in redox reactions.

Light-induced electrical effects in a liquid crystal BLM containing TCNQ.

Abstract— The light‐induced capacitance changes and also both photovoltage and photocurrent under continuous illumination have been investigated in pigmented liquid crystal bilayer membranes (PBLM)‡ containing TCNQ as photosensitizer with Na2SO3 electron donor on one side and methylene blue electron acceptor on the other side. The results have shown that TCNQ in cyanobiphenyl membrane produces a unique photoactive BLM system in which all three main parameters (conductivity, capacity and voltage across the membrane) are in a wide range altered by the light. It is shown that a TCNQ‐cyanobiphenyl charge transfer complex is responsible for the observed photochanges. The possible mechanism of photoinduced electrical effects in this type of PBLM is discussed.