Branching ratios in the β decays of N12 and B12

Absolute branching ratios to unbound states in C12 populated in the β decays of N12 and B12 are reported. Clean sources of N12 and B12 were obtained using the isotope separation on-line (ISOL) method. The relative branching ratios to the different populated states were extracted using single-alpha as well as complete kinematics triple-alpha spectra. These two largely independent methods give consistent results. Absolute normalization is achieved via the precisely known absolute branching ratio to the bound 4.44 MeV state in C12. The extracted branching ratios to the unbound states are a factor of three more precise than previous measurements. Branching ratios in the decay of Na20 are also extracted and used to check the results. © 2009 The American Physical Society.Supported by the Academy of Finland (Project No. 44875), by the Spanish Agency CICYT (Nos. FPA2007–62170 and FPA2007–62216), by the European Union Sixth Framework Programme “EURONS” (No. 506065), by the Swedish Research Council, and the Knut and Alice Wallenberg foundation.Peer Reviewe

Neutron field characteristics at radiation metrology laboratory of STUK

STUKin mittanormaalilaboratoriossa tehdään tilauksesta kalibrointeja ionisoivan säteilyn mittareille. Neutronisäteilyn osalta tarjolla on vapaa annosekvivalentti (H*(10)) aluevalvontamittareiden kalibrointiin. Tulevaisuudessa on nähtävissä tarvetta myös henkilöannosmittareiden kalibrointiin, jossa säteiltylaatu on henkilöannosekvivalentti Hp(10). Mittanormaalilaboratorio on aloittanut selvitystyön STUKin kalibrointihallien kelpoisuudesta tarkoitukseen. ISO-8529 standardi määrittelee edellytykset ja tarvittavat valmistavat mittaukset Hp(10) kalibrointeihin ja tämän standardin vaatimusten perusteella olemme tehneet varjokartiomittauksia ja Monte Carlo -simulaatioita nykyisistä tiloista ja neutronilähteistä. Ensimmäisessä vaiheessa simulaatiomallia testattiin laskemalla h*(10) annosnopeudet, koska näitä varten STUKin neutronimittareilla on primäärilaboratorioon jäljitettävissä oleva kalibrointi. Tässä julkaisussa käsitellään tarkemmin nämä mittaukset ja simuloinnit. Koska lasketut ja mitatut tulokset sopivat yhteen hyvin, projektia jatketaan tekemällä mittausvertailu henkilöannossuureella vuoden 2018 aikana

Compact laser radar based on a subnanosecond laser diode transmitter and a two-dimensional CMOS single-photon receiver

Abstract A pulsed TOF laser radar utilizing the single-photon detection mode has been implemented, and its performance is characterized. The transmitter employs a QW double-heterostructure laser diode producing 0.6 nJ∕100 ps laser pulses at a central wavelength of ∼810 nm. The detector is a single-chip IC manufactured in the standard 0.35-μmHV CMOS process, including a 9 × 9 single-photon avalanche diode (SPAD) array and a 10-channel time-to-digital converter (TDC) circuit. Both the SPAD array and the TDC circuit support a time gating feature allowing photon detection to occur only within a predefined time window. The SPAD array also supports a 3 × 3 SPADs subarray selection feature to respond to the laser spot wandering effect due to the paraxial optics and to reduce background radiation-induced detections. The characterization results demonstrate a distance measurement accuracy of þ∕ − 0.5 mm to a target at 34 m having 11% reflectivity. The signal detection rate is 28% at a laser pulsing rate of 100 kHz. The single-shot precision of the laser radar is ∼20 mm (FWHM). The deteriorating impact of high-level background radiation conditions on the SNR is demonstrated, as also is a scheme to improve this by means of detector time gating

A laser radar based on a “impulse-like” laser diode transmitter and a 2D SPAD/TDC receiver

Abstract A pulsed TOF laser radar has been implemented and its performance characterized. The transmitter applies a QW double-heterostructure laser diode producing 0.6 nJ/ 100 ps laser pulses at the central wavelength of ~ 817 nm. The detector is a single-chip IC, manufactured in the standard 0.35 μm HV CMOS process, including a 9×9 SPAD array and a 10-channel TDC circuit. Both the SPAD array and the TDC circuit support a time gating feature allowing photon detection only to occur within a predefined time window. The SPAD array also supports the sub-array selection feature in order to respond to the laser spot wandering effect due to paraxial optics. A sub-array is a 3×3 SPAD array freely chosen within a 9×9 SPAD array. The characteristic measurement results demonstrate the measurement range of tens of meters with a linearity precision +/- 0.5 mm to the 11% target reflectivity and at pulsing frequency of 100 kHz. The distance dependent detection rate varies from 28% to 500%, thus providing a high measurement rate. The single-shot precision is ~ 20 mm. The deteriorating impact of high-level background radiation conditions on the SNR has been demonstrated as well as a scheme to improve it by detector time gating

New ion-guide for the production of beams of neutron-rich nuclei between Z = 20 - 28

It has been shown for the first time that quasi- and deep-inelastic reactions can be successfully incorporated into the conventional Ion-Guide Isotope Separator On-Line (IGISOL) technique. This is of particular interest for characterizing the decay properties of refractory elements and is applied to neutron rich nuclei between Z = 20-28. As a first step of this project, the kinematics of quasi- and deep-inelastic reactions, such as {sup 197}Au({sup 65}Cu,X)Y, were studied. Based on these studies, a specialized IGISOL target chamber was designed and built. This chamber was tested in on- and off-line conditions at the Jyvaskyla IGISOL facility. Yields of radioactive, projectile-like species such as {sup 62,63}Co are about 0.8 ions/s/pnA corresponding to a total IGISOL efficiency of about 0.06%

New ion-guide for the production of beams of neutron-rich nucleibetween Z = 20 - 28

It has been shown for the first time that quasi- and deep-inelastic reactions can be successfully incorporated into the conventional Ion-Guide Isotope Separator On-Line (IGISOL) technique. This is of particular interest for characterizing the decay properties of refractory elements and is applied to neutron rich nuclei between Z = 20-28. As a first step of this project, the kinematics of quasi- and deep-inelastic reactions, such as {sup 197}Au({sup 65}Cu,X)Y, were studied. Based on these studies, a specialized IGISOL target chamber was designed and built. This chamber was tested in on- and off-line conditions at the Jyvaskyla IGISOL facility. Yields of radioactive, projectile-like species such as {sup 62,63}Co are about 0.8 ions/s/pnA corresponding to a total IGISOL efficiency of about 0.06%

Beta decay of neutron-rich 118Ag and 120Ag isotopes

b decays of on-line mass-separated neutron-rich 118Ag and 120Ag isotopes have been studied by using b-g and g-g coincidence spectroscopy. Extended decay schemes to the 118,120Cd daughter nuclei have been constructed. The three-phonon quintuplet in 118Cd is completed by including a new level at 2023.0 keV, which is tentatively assigned the spin and parity of 24 1 . The intruder band in 118Cd is proposed up to the 41 level at 2322.4 keV. The measured b-decay half-life for the high-spin isomer of 120Ag is 0.4060.03 s. Candidates for the three-phonon states, as well as the lowest members of the intruder band in 120Cd, are also presented. These data support the coexistence of quadrupole anharmonic vibration and proton particle-hole intruder excitations in 118,120Cd.peerReviewe

Isomers of astrophysical interest in neutron-deficient nuclei at masses A = 81, 85 and 86

Decay properties of neutron-deficient exotic nuclei close to A=80 have been investigated at the IGISOL facility. The studied nuclei, 81Y, 81Sr, 81mKr, 85Nb, 85Zr, 86Mo and 86Nb, were produced by a 32S beam from the Jyväskylä isochronous cyclotron on 54Fe and natNi targets. The internal conversion coefficient for a 190.5 keV isomeric transition in 81mKr has been measured and the internal transition rate has been determined. The internal transition rate has been used to estimate a neutrino capture rate on 81Br, which yields a log ft of 5.13±0.09 for the reaction 81Br( ν, e-)81mKr. A new isomer with a half-life of 3.3±0.9 s has been observed in 85Nb. The existence of an earlier reported isomer with a half-life of 56 s in 86Nb has not been confirmed.peerReviewe