Detection Of Heavy Ions Research Articles

Calorimetric low temperature detectors for low-energetic heavy ions and their application in accelerator mass spectrometry

The energy-sensitive detection of heavy ions with calorimetric low temperature detectors was investigated in the energy range of E=0.1-1 MeV/amu, commonly used for accelerator mass spectrometry (AMS). The detectors used consist of sapphire absorbers and superconducting aluminum transition edge thermometers operated at T approximately 1.5 K. They were irradiated with various ion beams (13C, 197Au, 238U) provided by the VERA tandem accelerator in Vienna, Austria. The relative energy resolution obtained was DeltaE/E=(5-9) x 10(-3), even for the heaviest ions such as 238U. In addition, no evidence for a pulse height defect was observed. This performance allowed for the first time to apply a calorimetric low temperature detector in an AMS experiment. The aim was to precisely determine the isotope ratio of 236U/238U for several samples of natural uranium, 236U being known as a sensitive monitor for neutron fluxes. Replacing a conventionally used detection system at VERA by the calorimetric detector enabled to substantially reduce background from neighboring isotopes and to increase the detection efficiency. Due to the high sensitivity achieved, a value of 236U/238U=6.1 x 10(-12) could be obtained, representing the smallest 236U/238U ratio measured at the time. In addition, we contributed to establishing an improved material standard of 236U/238U, which can be used as a reference for future AMS measurements.

Cherenkov radiation from relativistic heavy ions taking account of their slowing down in radiator

Combining the SRIM’06 computer code and the formula for spectral-angular distribution of radiation from a particle moving in a medium in arbitrary trajectory, we studied numerically the structure of angular distributions of Cherenkov radiation from moderately relativistic heavy ions (RHI) taking into account the decrease of the ion velocity due to stopping in the radiator. The results obtained clearly show that the width and the fine structure of the Cherenkov radiation in the vicinity of the Cherenkov cone depend strongly on several factors, e.g. the mean and total energy losses, the radiator thickness, the square of the ion charge, the emission wavelength and the refractive index of the radiator material. This might be useful for experiments using RICH detectors for relativistic heavy ions.

Design and simulation of charge sensitive preamplifier with CMOS FET implemented as feedback capacitor Cfp

In this paper, to design a new preamplifier for optimum performances with charged-particle or heavy-ion detectors, the CMOS FET is implemented as a feedback capacitor C fp. so that the entire system should be built only with MOSFET. This work is a revolution design because to realize an ASIC for a preamplifier circuit, the capacitor will also be included. We succeed after a simulation to maintain a rise time less than 3 ns, the output resistance less than 94 Ω and the linearity almost good.

The ALICE DAQ Online transient data storage system

ALICE is a dedicated heavy-ion detector to exploit the physics potential of nucleus-nucleus (lead-lead) interactions at LHC energies. Running in heavy-ion mode the data rate from event building to permanent storage is expected to be around 1.25 GB/s. To continue data recording even in the event of hardware failure or connection problems, a large disk pool has been installed at the experiment's site as buffering layer between the DAQ and the remote (∼5km) tape facility in the CERN Computing Centre. This Transient Data Storage (TDS) disk pool has to provide the bandwidth to be able to simultaneously absorb data from the event building machines and to move data to the tape facility. The aggregated bandwidth of the TDS is expected to exceed 3 GB/s in mixed I/O traffic. Extensive tests have been carried out on various hardware and software solutions with the goal to build a common file space shared by ∼60 clients, whilst still providing maximum bandwidth per client (∼400MB/s, 4Gbps Fibre Channel), fail-over safety and redundancy. This paper will present the chosen hardware and software solution, the configuration of the TDS pool and the various modes of operation in the ALICE DAQ framework. It will also present the results of the performance tests carried out during the last ALICE Data Challenge.

Commissioning of the ALICE data acquisition system

ALICE (A Large Ion Collider Experiment) is the heavy-ion detector designed to study the physics of strongly interacting matter and the quark-gluon plasma at the CERN Large Hadron Collider (LHC). A flexible, large bandwidth Data Acquisition System (DAQ) has been designed and deployed to collect sufficient statistics in the short running time foreseen per year for heavy ions and to accommodate very different requirements originated from the 18 sub-detectors. The Data Acquisition and Test Environment (DATE) is the software framework handling the data from the detector electronics up to the mass storage. This paper reviews the DAQ software and hardware architecture, including the latest features of the final design, such as the handling of the numerous calibration procedures in a common framework. We also discuss the large scale tests conducted on the real hardware to assess the standalone DAQ performances, its interfaces with the other online systems and the extensive commissioning performed in order to be ready for cosmics data taking scheduled to start in November 2007. The test protocols followed to integrate and validate each sub-detector with DAQ and Trigger hardware synchronized by the Experiment Control System are described. Finally, we give an overview of the experiment logbook, and some operational aspects of the deployment of our computing facilities. The implementation of a Transient Data Storage able to cope with the 1.25 GB/s recorded by the event-building machines and the data quality monitoring framework are covered in separate papers.

Low Hg(II) ion concentration electrical detection with AlGaN/GaN high electron mobility transistors

Thioglycolic acid functionalized Au-gated AlGaN/GaN high electron mobility transistors (HEMTs) were used to detect mercury(II) ions. The drain current of the HEMT sensors monotonically increased with the mercury(II) ion concentration from 1.5 × 10−8 to 4 × 10−8 M. The drain current reached equilibrium around 15–20 s after the concentrated Hg ion solution added to the gate area of the HEMT sensors. The effectiveness of the thioglycolic acid functionalization was evaluated with a surface contact angle study. The results suggest that portable, fast response, and wireless-based heavy metal ion detectors can be realized with AlGaN/GaN HEMT-based sensors.

Threshold ss of superheated emulsion detector to heavy ions

Superheated emulsion has made its widespread application for the detection of neutron. One of the recent developments of this detector is the detection of heavy ions. The present work includes the nucleation in superheated emulsion detector by heavy ions. In this report, the experiments with 40Ar ( 500 MeV / u ) and 20Ne ( 230 MeV / u ) are presented and a correction term has been added in the count rate analysis. The threshold degree of meta stability, ‘ ss th ’, is determined by observing the variation of normalized response of the detector as a function of operating temperature. The ‘ ss th ’ for the two ions are estimated using the relationships between critical energy and the track averaged LET.

Radiation-Tolerant, SRAM-FPGA Based Trigger and Readout Electronics for the ALICE Experiment

The ALICE detector is a dedicated heavy-ion detector at the large hadron collider which is commissioned end of 2007 at CERN. The ALICE triggers are handled by the central trigger processor and distributed to all sub-detectors, amongst other the time projection chamber and the photon spectrometer. The front end electronics of the time projection chamber and the photon spectrometer share many of the same components. The photon spectrometer provides the trigger system with level 0 and level 1 triggers (e.g., high-P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> photons) by the use of several trigger router units and a trigger-OR board. The trigger electronics and the front end electronics are situated close to the collision-point, and errors due to radiation effects are to be expected. This article gives an overview of the trigger system from trigger generation with the photon spectrometer to trigger reception of the front end electronics of both detectors. How to deal with the possible effects of the radiation environment on the electronics that do trigger handling was evaluated.

Rapid Electrical Detection of Hg(II) Ions with AlGaN/GaN High Electron Mobility Transistors

Bare Au-gated and thioglycolic acid functionalized Au-gated AlGaN/GaN high electron mobility transistors (HEMTs) were used to detect mercury(II) ions. Fast detection of less than 5 seconds was achieved for thioglycolic acid functionalized sensors. This is the shortest response time ever reported for mercury detection. Thioglycolic acid functionalized Au-gated AlGaN/GaN HEMT based sensors showed 2.5 times larger response than bare Au-gated based sensors. The sensors were able to detect mercury (II) ion concentration as low as 10-7 M. The sensors showed an excellent sensing selectivity of more than 100 for detecting mercury ions over sodium or magnesium ions. The dimensions of the active area of the sensor and the entire sensor chip are 50 µm × 50 µm and 1 mm × 5 mm, respectively. Therefore, portable, fast response, and wireless based heavy metal ion detectors can be realized with AlGaN/GaN HEMT based sensors.

Nanoparticles of K2Ca2(SO4)3:Eu as effective detectors for swift heavy ions

The modification of thermoluminescence (TL) and photoluminescence (PL) properties of K2Ca2(SO4)3:Eu nanoparticles by swift heavy ions (SHI), irradiation is studied. Pellets form of the nanomaterials were irradiated by 48 MeV Li3+, 75 MeV C6+, and 90 MeV O7+ ion beams. The fluence range is 1×109−1×1013 ions/cm2. The modification in TL glow curves of the nanomaterials irradiated by Li3+, C6+, and O7+ ion beams are essentially similar to those induced by γ-ray irradiation. These glow curves have single peaks at around 427 K with a small variation in their positions by around ±3 K. The TL intensity of the ion beams irradiated nanomaterials is found to decease, while going from low to high atomic number (Z) ions (i.e., Li3+→O7+). The TL response curve of the pellets irradiated by Li3+ ions is linear in the whole range of studied fluences. The curves for C6+ and O7+ irradiated samples are linear at lower fluences (1×109–1×1012 ion/cm2) and then saturate at higher fluence. These results for the nanomaterials are much better than that of the corresponding microcrystalline samples irradiated with a Li3+ ion. The curves were linear up to the fluence 1×1011 ion/cm2 and then become sublinear at higher fluences. The TL efficiency values of K2Ca2(SO4)3:Eu nanoparticles irradiated by 48 MeV Li3+, 75 MeV C6+, and 90 MeV O7+ ion beams have been measured relative to γ rays of C60o and are found to be 0.515, 0.069, and 0.019, respectively. This value for the Li3+ ion (0.515) is much higher than that of the corresponding microcrystalline material (0.0014). These superiorities for the nanomaterials make K2Ca2(SO4)3:Eu nanophosphor a suitable candidate for detecting the doses of swift heavy ions. PL studies on the ion beams irradiated and unirradiated K2Ca2(SO4)3:Eu nanoparticles show a single band at 384 nm, which could be assigned to Eu2+ emission, while the microcrystalline form of this material shows emission at 436 nm. This wide blueshift in PL of the nanomaterial could be attributed to the extension of the band gap of Eu2+ due to the absence of crystal field effects.

A detector for filtering γ-ray spectra from weak fusion–evaporation reactions out of strong background and for Doppler correction: The recoil filter detector, RFD

A detector has been designed and built to assist in-beam γ-ray spectroscopy with fusion–evaporation reactions. It measures with high efficiency the evaporation residues that recoil out of a thin target into the angular interval from 1.8° to 9.0° at an adjustable distance of 1000–1350 mm from a target, in coincidence with γ-rays detected in a Ge-detector array. This permits filtering of such γ-rays out of a much stronger background of other reaction products and scattered beam. Evaporation residues are identified by their time-of-flight and the pulse height using a pulsed beam. The velocity vector of the γ-emitting recoil is also measured in the event-by-event mode, facilitating to correct the registered γ-ray energy for the Doppler shift, with the resulting significant improvement of the energy resolution. The heavy-ion detection scheme uses emission of secondary electrons caused by the recoiling ions when hitting a thin foil. These electrons are then electrostatically accelerated and focused onto a small scintillator that measures the summed electron energy, which is proportional to the number of electrons. The detector is able to operate at high frequency of the order of 1 MHz and detect very heavy nuclei with as low kinetic energy as 5 MeV. The paper describes the properties of the detector and gives examples of measurements with the OSIRIS, GAREL+ and EUROBALL IV γ-ray spectrometers. The usefulness of the technique for spectroscopic investigations of nuclei with a continuous beam is also discussed.

Fast electrical detection of Hg(II) ions with AlGaN∕GaN high electron mobility transistors

Bare Au gated and thioglycolic acid functionalized Au-gated AlGaN∕GaN high electron mobility transistors (HEMTs) were used to detect mercury (II) ions. Fast detection of less than 5s was achieved for thioglycolic acid functionalized sensors. This is the shortest response time ever reported for mercury detection. Thioglycolic acid functionalized Au-gated AlGaN∕GaN HEMT based sensors showed 2.5 times larger response than bare Au-gated based sensors. The sensors were able to detect mercury (II) ion concentration as low as 10−7M. The sensors showed an excellent sensing selectivity of more than 100 for detecting mercury ions over sodium or magnesium ions. The dimensions of the active area of the sensor and the entire sensor chip are 50×50μm2 and 1×5mm2, respectively. Therefore, portable, fast response, and wireless based heavy metal ion detectors can be realized with AlGaN∕GaN HEMT based sensors.

Spectroscopy of neutron-rich Pd and Cd isotopes near A=120

New high-spin levels have been identified in the nucleus 120Pd from analysis of the coincidence gamma rays observed in the 238U(α, f γ γ γ ) reaction. Recoiling fragments were detected with the Rochester heavy-ion detector array, CHICO, in coincidence with gamma-rays using Gammasphere. An A=110-130 mass-gated γ − γ − γ cube from this experiment was constructed and analyzed for coincident gamma-rays in several nuclei near A=120. New results for neutron-rich 118Pd and 120Pd have been obtained. The 120Pd level scheme was extended to spin of 10+ by building on the new low-energy gamma rays identified in decay studies of 120Rh. The details of the 118Pd level scheme derived from this work are compared to previous work. The systematics of the yrast levels in even-even Pd and Cd isotopes are presented and the symmetry of energy levels around N = 68 is discussed. A new 10+ level in 124Cd has been observed. The population intensity of even-even neutron-rich Cd isotopes is deduced, indicating that nuclides near 120Cd are preferentially populated following alpha-induced fission of 238U.

The control system for the front-end electronics of the ALICE time projection chamber

The ALICE detector is a dedicated heavy-ion detector currently built at the Large Hadron Collider (LHC) at CERN. The detector control system (DCS) covers the task of controlling, configuring and monitoring the detector. One sub-system is the control system for the Front-end electronics of the time projection chamber (TPC). It controls in total 216 readout systems with 4356 Front-End Cards serving roughly 560 000 channels. The system consists of a large number of distributed nodes in a layer-structured hierarchy. The low-level node controlling the Front-end electronics is an embedded computer system, the DCS board, which provides the opportunity to run a light-weight Linux system on the card. The board interfaces to the Front-end electronics via a dedicated hardware interface and connects to the higher DCS-layers via the DIM communication framework over Ethernet. Since the experiment will be running in a radiation environment, fault tolerance, error correction and system stability in general are major concerns. Already the low level devices carry out intelligent error handling and act automatically upon several conditions. This paper presents the architecture of the system, the application of the DCS board and experiences from integration tests.

A spectrometer for low energy heavy ion ERDA

An ERDA detector telescope consisting of a time-of-flight (ToF) system combined with a gas ionization chamber (GIC) has been developed which is specialized for the identification of very low energy ions. Equipped with a large area patterned silicon nitride entrance window of 130 nm thickness, the GIC allows heavy ion detection well below 1 MeV with sufficient resolution for particle identification. The ToF system has a start detector with a diamond-like carbon (DLC) foil of only 0.5 μg/cm 2, which warrants excellent energy resolution for depth profiling. The system has been tested with 127I, 197Au and 48Ti projectiles of energies between 1.5 and 12 MeV. In the low mass range (up to 30 amu) the mass resolution is better than 1 in 35 at a recoil energy of approximately 3 MeV. A depth resolution of 1.5 nm (FWHM) has been obtained at a TiO 2 surface using 1.5 MeV 127I projectiles. The spectrometer is well suited for high resolution near-surface ERDA analysis even at accelerators with very low beam energies.

First results of Chinese particle instruments in the Double Star Program

Abstract. Double Star Program (DSP) aims to investigate the trigger mechanism and physical models of geomagnetic storms and substorms. The DSP involves two satellites: the equatorial satellite of DSP (TC-1 in China) and the polar satellite of DSP (TC-2 in China). On board the two satellites of TC-1 and TC-2, there are four kinds of particle instruments developed by the Center for Space Science and Applied Research (CSSAR), namely: the High Energy Electron Detector (HEED, TC-1, 2), the High Energy Proton Detector (HEPD, TC-1, 2), the High Energy Heavy Ion Detector (HID, TC-1, 2) and the Low Energy Ion Detector (LEID, TC-2). HEED, HEPD and HID were developed and calibrated in China. The LEID was developed in China and calibrated in France. This paper introduces the scientific objectives and characteristics of each instrument, their status and some preliminary results.

Characteristics of Superconducting Series Array Tunnel Junctions for Heavy Ions

Heavy ion detection experiments were carried out with superconducting series array tunnel junctions. /sup 40/Ar beam from linear accelerator was introduced to a cryostat and stopped in a substrate on which series array tunnel junctions were fabricated. An energy resolution of 4.2% was obtained for 191 MeV /sup 40/Ar, but linearity proved poor for energy ranges from 136 MeV to 191 MeV.

Heavy Ions with CMS: The Central Region

The potential of CMS as a heavy ion detector is described with special emphasis on the study of the central rapidity region. The detector provides excellent measurements of leptons, photons, gauge bosons, jets and quarkonia. Thus CMS serves as an unbiased detector for Pb+Pb events at \(\sqrt {S_{nn} } = 5.5\) TeV.

First tests of a thin natural diamond detector as an energy spectrometer for low-energy heavy ions

Diamond is an attractive alternative to silicon as a heavy ion detector owing to its exceptional radiation hardness and very fast timing. These remarkable properties of diamond allow one to expect that diamond detectors can outperform silicon detectors and ionization chambers for many applications, in particularly, for heavy ion accelerator mass spectrometry (AMS) measurements. However, most reported diamond particle detectors have been based on polycrystalline chemical-vapor-deposited diamond films and exhibited poor energy resolution (due to loss of charge carriers in the grain boundaries) resulting in limited applications, primarily for counting ions at hundreds of MeV/u. In this paper the evaluation of a thin single-crystal natural diamond detector as an energy spectrometer for 13C, 180Hf, and 238U ions in the energy range from 12 to 38 MeV is presented. The influence of “priming” and “polarization” effects is discussed. Initial measurements of energy resolution, stability and radiation hardness of the natural diamond detector have demonstrated its suitability for heavy ion AMS, in spite of some technical problems to be solved.

Noise analysis for calorimetric low-temperature detectors for heavy ions

The energy resolution of calorimetric low-temperature detectors for heavy ions has been analyzed. It is shown that the contribution of base line noise is small. The energy resolution is determined by intrinsic fluctuations of the detector signal. An incomplete energy thermalization during the stopping process of the heavy ion, the dependence of signal shape on impact position and fluctuations of the Al-TES thermometer response are considered as main sources of detector line broadening. Test measurements with 5MeV α-particles are presented.