Beam test results of an ion-implanted capacitively coupled silicon strip detector processed on a 100 mm silicon wafer

A capacitively coupled silicon strip detector with 50 μm readout pitch has been tested in a pion beam at CERN. The spatial resolution of the detector equipped with LSI readout chips was 4.9 μm and the most probable signal-to-single-channel noise ratio was 31.     

Ion-implanted capacitively coupled silicon strip detectors with integrated polysilicon bias resistors processed on a 100 mm wafer

Double-sided silicon strip detectors with integrated coupling capacitors and polysilicon resistors have been processed on a 100 mm wafer. A detector with an active area of 19 × 19 mm² was connected to LSI readout electronics and tested. The strip pitch of the detector is 25 μm on the p-side and 50 μm on the n-side. The readout pitch is 50 μm on both sides. The number of readout strips is 774 and the total number of strips is 1161. On the p-side a signal-to-noise of 35 has been measured using a ⁹⁰Sr β-source. The n-side has been studied using a laser.     

VIKING, a CMOS low noise monolithic 128 channel frontend for Si-strip detector readout

A low noise Si-strip detector readout chip has been designed and built in 1.5 μm CMOS technology. The chip is optimized w.r.t. noise. Measurements with this chip connected to several silicon strip detectors are presented. A noise performance of ENC = 135 e⁻ + 12 e⁻/pF and signal to noise ratios between 40–80, depending on the detector, for minimum ionizing particles traversing silicon has been achieved.     

MEDUSA-32: A low noise, low power silicon strip detector front-end electronics, for space applications

In this report we describe a mixed analog-digital integrated circuit (IC) designed as the front-end electronics for silicon strip-detectors for space applications. In space power consumption, compactness and robustness become critical constraints for a pre-amplifier design. The IC is a prototype with 32 complete channels, and it is intended for a large area particle tracker of a new generation of gamma ray telescopes. Each channel contains a charge sensitive amplifier, a pulse shaper, a discriminator and two digital buffers. The reference trip point of the discriminator is adjustable. This chip also has a custom PMOSFET transistor per channel, included in order to provide the high dynamic resistance needed to reverse-bias the strip diode.

The digital part of the chip is used to store and serially shift out the state of the channels. There is also a storage buffer that allows the disabling of non-functioning channels if it is required by the data acquisition system.

An input capacitance of 30 pF introduced at the input of the front-end produces less than 1000 electrons of RMS equivalent noise charge (ENC), for a total power dissipation of only 60 μW per channel.

The chip was made using Orbit's 1.2 μm double poly, double metal n-well low noise CMOS process. The dimensions of the IC are 2400 μm × 8840 μm.     

Mechanical properties of WC/Co cemented carbide with larger WC grain size

The mechanical properties of WC/Co cemented carbide with WC grain size of up to 30 μm are investigated through compressive and transverse rupture tests, because it is now to produce WC/Co cemented carbide of which grain sizes are from 20 to 30 μm. From testing specimens with a WC grain size of 3–30 μm and Co content of 5–20 wt.%, it is found that WC/Co cemented carbide with larger WC grains (20–30 μm) exhibit ductility, whereas smaller-grained materials are characteristically brittle.     

Residual stress development in Pb(Zr,Ti)O3/ZrO2/SiO2 stacks for piezoelectric microactuators

The residual stress of multilayers in piezoelectric microelectromechanical systems structures influences their electromechanical properties and performance. This paper describes the development of residual stress in 1.6 μm Pb(Zr_0.52,Ti_0.48)O₃ (PZT)/0.3 μm ZrO₂/0.5 μm SiO₂ stacks for microactuator applications. The residual stresses were characterized by wafer curvature or load-deflection measurements. PZT and zirconia films were deposited on 4-in. (100) silicon wafers with 0.5 μm thick thermally grown SiO₂ by sol–gel processes. After the final film deposition, the obtained residual stress of PZT, ZrO₂, and SiO₂ were 100–150, 230–270, and − 147 MPa, respectively. The average stress in the stack was  80 MPa. These residual stresses are explained in terms of the thermal expansion mismatch between the layers and the substrate. Load-deflection measurements were conducted to evaluate localized residual stresses using released circular diaphragms. The load-deflection results were consistent with the average stress value from the wafer curvature measurements. It was found that more reasonable estimates of the stack stresses could be obtained when mid-point vertical deflection data below 6 μm were used, for diaphragms 0.8–1.375 mm in diameter.     

Protecting aluminum alloy from particle-impact ignition with an Al2O3 film

Bare aluminum alloy is compared to soft-anodized aluminum alloy (oxide film thickness 5 μm, 10 μm, 20 μm, or 50 μm) for susceptibility to ignition by supersonic particle impact in pure oxygen. The particle diameter ranged from 1600 μm to 2000 μm, temperature ranged from 220 K to 672 K and oxygen pressure was 27.6 MPa. The event of ignition was recorded on video tape. The results of ignition frequency are reported as a Logistic Regression Model over the variable space. In addition, the impact process was simulated using the computer code ZEUS to identify ignition temperatures and ignition sites as well as to qualitatively describe the mechanism of protection offered by the soft-anodized oxide film. Significant improvement against particle-impact ignition was achieved through the use of the anodized oxide film.     

Concentration effects on the IR-luminescent channels for Er- and Ho-doped LiYF4 crystals

In this paper we report the ideal concentrations for the main infrared laseof channels r the Er³⁺- and Ho³⁺-doped LiYF₄ (YLF) crystals, under Xe lamp pumping. The number of photons per luminescent channel was also obtained for both ions. It was determined that 10–20% of Erbium at.wt is the ideal concentration for laser action at 2.74 μm, as well as the 1.7% Er-doped YLF crystal is the best one for lasing at 0.85, 1.23, and 1.72 μm under flashlamp pumping. The present method is a good approach in order to indicate the ideal concentration for an optimized four-level laser system. For the transitions at 1.62 μm (Er:YLF) and at 2.07 μm (Ho:YLF) it was observed that the luminescence intensities are maximized in the concentration range (25–35)% for Er ions and in the range (10–15)% for Ho ions in the YLF crystals. However, these concentration values are much higher than the ones used in a practical three-level laser system.     

Heat treatment and wear characteristics of Al/SiCp composites fabricated by duplex process

This study was undertaken to investigate the effects of alloying elements and heat treatment on the microstructures, wear resistance, and heat resistance of Al–Si–Cu–Mg–(Ni)/SiC_p composites fabricated by a duplex process that consists of squeeze infiltration (1st step) followed by squeeze casting (2nd step). This duplex process produces a homogeneous distribution of SiC_p in Al alloy. The hardness of the composites increased with decrease in SiC_p size, and also with Ni addition in both the as-cast and the as-aged specimens. Compared with 5 and 10 μm SiC_p reinforced Al composites, the aging time to obtain the peak hardness was shortened for 3 μm SiC_p reinforced Al composite, because of higher density dislocations on the periphery of SiC_p in the matrix. However, the Al composite reinforced with 10 μm SiC_p was found to have the lowest wear amount as compared with 3 and 5 μm SiC_p composites. The amount of wear in Al/SiC_p composites decreased with increase of the sliding speed because abrasive wear occurred under low sliding speed and block-type wear debris occurred under high sliding speed.     

Nonlinear optical properties of the flux grown RbTiOPO4 crystal

Refractive indices of flux grown RbTiOPO₄ (RTP) were measured in the wavelength interval 0.406 to 1.064 μm and Sellmeier equation coefficients were calculated. Phase-matching curves for second harmonic generation from radiation with wavelengths of 1.064 μm and 1.079 μm were obtained. RTP nonlinear optical properties are compared to those of KTP. Second-harmonic generation in RTP crystal is carried out with the efficiency of 65%.     

Aggregation morphology of synthetic peptidic amphiphiles

Peptidic amphiphiles containing various homo-oligopeptides were synthesized. Their aggregation morphologies in aqueous dispersion were studied using dark-field optical microscopy. The amphiphile containing three glycine residues formed amorphous precipitates. The amphiphile containing three sarcosine residues formed novel twisted ribbon-like aggregates with a long pitch (15–25 μm). The amphiphile containing three proline residues formed fibrous helical superstructures (50–70 μm in length). The last two morphologies were stable only at temperatures below the phase transition temperature. Different aggregation morphologies of the peptidic amphiphiles in aqueous dispersion were observed in the presence and absence of amide (NH) protons. Small amounts of additives altered the morphological structure of the aggregates on incubation.     

CD: A double sided silicon strip detector for radioactive nuclear beam experiments

A very compact double sided silicon strip detector array is described, designed for use in reaction studies involving radioactive nuclear beams. It is small enough to fit inside a large solid angle γ-detector array and will enable Doppler-shift corrections at energies in the vicinity of the Coulomb barrier. The detector provides sufficient energy and time-of-flight resolution for the identification of light reaction products and can be set up to cover a substantial part of the scattering angular distribution with good resolution.

The device is available in thicknesses of up to 500 μm to stop all interesting reaction products. Moreover, a very thin (35–40 μm) variant of this detector is described that can be used as an energy loss detector in a ΔE−E telescope geometry followed by a detector that measures the residual energy. This provides additional particle identification capabilities, e.g. in light exotic nuclei induced reactions. First results from a commissioning run using a post-accelerated radioactive beam are presented.     

Hypervelocity impact testing of micrometeorite capture cells in conjunction with a PVDF thin-film velocity/trajectory sensor and a simple plasma velocity detector

Five different small particle capture cell designs were evaluated for their ability to capture fragments and residue from 10–200 μm diameter glass projectiles and oblong olivine crystals impacting at 1–15 km/s in sufficient quantity for chemical and isotopic analyses. Aluminum multi-foils (0.1–100 μm thick with ≈10, 000 and 1800 μm spacing), foil covered germanium crystals, and 0.50 and 0.120 g/cm³ Aerogels, were positioned behind either multi-film (1.4–6.0 μm thick) polyvinylidene fluoride (PVDF) velocity/trajectory sensor devices of a simple wire-grid plasma velocity detector. All capture cells collected significant amounts of impactor debris behind the PVDF sensors from nominal 100 μm diameter glass projectiles and olivine crystals which struck the sensor at velocities up to 6.4 km/s. At velocities >8 km/s little or no debris penetrated the second PVDF film. Results were incolsive for velocities between 6.5 and 8 km/s. Plasma detector results showed identifiable impactor residue on Al foils for velocities up to 8.7 km/s and impact tracks with apparent debris imbedded in the Aerogels for velocities up to 12.7 km/s. Maximum foil penetration of glass spheres and olivine crystals were the same, but more particulate debris was associated with olivine crystal ipacts versus glass impacts. Foil spacing beyond one particle diameter had no effect on total penetration. Aerogels are identified as a capture cell media that warrants further investigation. The Al multi-foil capture cell with 100 μm net spacers is identified as the most effective of the other designs and offers the advantages of compact structure, low secondary ejecta from impacts, and easy recovery of impactor debris for analysis.     

Luminescence quantum efficiency of F2 and F3 centers in LiF crystals

F^-₂ color center in LiF crystals is a unique specie of color centers concerning its photothermal stability, its broad absorption band, centered at 0.96 μm, and its broad emission band peaking at 1.12 μm, being a tunable laser operating in the range from 1.08 μm to 1.22 μm. The luminescence quantum efficiency of the main transition in the laser optical cycle was determined, at room temperature, and its value is 0.5 ± 0.1. This value was obtained using a method correlating the absorption, excitation and photoacoustic spectra. Besides, the luminescence quantum efficiency of the fundamental transition of the F^-₃ color center was determined. Also was estimated the energy transfer efficiency due to the overlapping of the F^-₃ center emission and the F^-₂ center absorption bands. Possible nonradiative deexcitation mechanisms accounting for the small luminescence quantum efficiency of the F^-₂ color centers in LiF are also discussed.     

Relationship Between Particle Size and Dissolution Rate of Bulk Powders and Sieving Characterized Fractions of two Qualities of Orthoboric Acid

We have carried out a study of the particle size distribution and aqueous dissolution rate of two commercially available qualities of orthoboric acid, labeled “crystal” (ABC) and “powder” (ABP). In a previous work, we have shown that the two commercial qualities of orthoboric acid chosen as model compound (“powder” and “crystal”) are related to the same crystal network in spite of their dvferent names. However, these two qualities have very different size particle distributions, as previously determined by sieving and confirmed by the present laser light scattering study. Dissolution testing is performed under sink conditions and show that the bulk ABC quality dissolves far more rapidly that the bulk ABP quality, For each quality, dissolution rates of four sieved particle size fractions (0-90 μm; 90-125 μm; 125-180 μm; 180-250 μm) were compared. Concerning the ABC quality, comparisons were also done with three other particles size fractions: 250-355 μm, 355-500 μm, and 500-710 μm. This study used the dQ/dt versus t profile. Dissolution profiles of the fractions enclosing particles with a size superior to 125 μm are very close. On the other hand, fractions enclosing particles with a size smaller than 90 μm present a different profile and a slower rate of dissolution.     

Performance of a liquid argon preshower detector integrated with an Accordion calorimeter

A prototype liquid argon preshower detector with a strip granularity of 2.5 mm has been tested at the CERN SPS in front of a liquid argon Accordion calorimeter. For charged tracks a signal-to-noise ratio of 9.4 and a space resolution of 340 μm were measured; the rejection power against overlapping photons produced in the decay of 50 GeV π⁰'s is larger than 3; the precision on     

A digital X-ray imaging system based on silicon strip detectors working in edge-on configuration

We present the energy resolution and imaging performance of a digital X-ray imaging system based on a 512-strip silicon strip detector (SSD) working in the edge-on configuration. The SSDs tested in the system are 300 μm thick with 1 or 2-cm-long strips and 100 μm pitch. To ensure a very small dead area of the SSD working in edge-on configuration, the detector is cut perpendicular to the strips at a distance of only 20 μm from the end of the strips. The 512-strip silicon detector is read out by eight 64-channel integrated circuits called DEDIX [Grybos et al., IEEE Trans. Nucl. Sci. NS-54 (2007) 1207]. The DEDIX IC operates in a single photon counting mode with two independent amplitude discriminators per channel. The readout electronic channel connected to a detector with effective input capacitance of about 2 pF has an average equivalent noise charge (ENC) of about 163 el. rms and is able to count 1 Mcps of average rate of input pulses. The system consisting of 512 channels has an excellent channel-to-channel uniformity—the effective threshold spread calculated to the charge-sensitive amplifier inputs is 12 el. rms (at one sigma level). With this system a few test images of a phantom have been taken in the 10–30 keV energy range.     

Preparation of (Ti1−xAlx)N films from mixed alkoxide solutions by plasma CVD

(Ti_1−xAl_x)N films were prepared on a Si wafer at 700°C from toluene solution of alkoxides (titanium tetraetoxide and aluminum tri-butoxide) in an Ar/N₂/H₂ plasma by the thermal plasma chemical vapor deposition (CVD) method. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, electrical resistivity, and Vickers micro-hardness. Single phase TiN formed at an Al atomic fraction of 0–0.2, with a mixed TiN and AlN phase occurring up to 0.6 and single phase AlN forming above 0.8. The films had relatively sooth surfaces, 0.4 μm thick at an Al atomic fraction of 0.2, and thickened with increasing Al fraction. The atomic concentration of Ti, Al, N, O, and C determined from their respective XPS areas showed that the Ti and Al contents of the films changes with the solution composition in a complementary way. The impurities were about 10 at.% oxygen and carbon. The electrical resistivity was almost unchanged from the value of 10³ μΩ cm at 0–0.6 Al but then suddenly increased to 10⁴ μΩ cm at higher Al contents. The hardness showed a synergic maximum of about 20 GPa at an Al fraction of 0.6–0.8.     

CHICSi—a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. II. Detectors

We describe the detectors for identification of charged particles and fragments in CHICSi, a large solid angle multi-telescope system mounted inside an ultra-high vacuum (UHV), cluster-jet target chamber. CHICSi performs nuclear reaction experiments at storage rings. The telescopes consist of a first very thin, 10–14 μm Si detector, a second 300 μm (or possibly 500 μm) ion implanted Si detector supplemented by a 6 mm GSO(Ce) scintillator read out by a photodiode (PD) or by a third 300 μm Si detector. The telescopes provide full charge separation up to Z=17 and mass resolution up to A=9 in the energy range 0.7–60A MeV. The thin p-i-n diode detector, etched out from a 280 μm Si wafer, and the GSO/PD detector, both exclusively developed for CHICSi, provide an energy resolution 8%, while the standard 300 μm detectors have 2% energy resolution. Radiation stability of the Si detectors is confirmed up to an integrated flux of 10¹⁰ alpha particles. The GSO detector has 70% light collection efficiency with the optical coupling to the PD a simple open, 0.2 mm, gap. A new method, developed to perform absolute energy calibration for the GSO/PD detector is presented.     

Radiation and cryogenic test results with a monolithic GaAs preamplifier in C-HFET technology

We report test results with a monolithic GaAs preamplifier fabricated in industrial C-HFET technology irradiated with a total dose of 10¹⁴ neutrons/cm² and 100 Mrad γ radiation and operated under cryogenic conditions. The measured gate current of the input transistor of a few nA increases by < 10% after irradiation. For a 330 μm input FET width, the equivalent noise charge (ENC) is typically 145 electrons per pF total input capacitance at a shaping time of 25 ns (bipolar) before irradiation and changes approximately by 10% after irradiation. Under cryogenic operation the corresponding input referred noise decreases by roughly a factor of two.