A simple soil mass correction for a more accurate determination of soil carbon stock changes.

Agricultural soils can act as a sink for large quantities of soil organic carbon (SOC) but can also be sources of carbon to the atmosphere. The international standard for assessing SOC stock and measuring stock change stipulates fixed depth sampling to at least 30 cm. The tendency of bulk density (BD) to decrease with decreasing disturbance and increasing SOC concentration and the assumption of constant SOC and BD within this depth profile promotes error in the estimates of SOC stock. A hypothetical but realistic change in BD from 1.5 to 1.1 g cm-3 from successive fixed depth sampling to 30 cm underestimates SOC stock change by 17%. Significant effort has been made to evaluate and reduce this fixed depth error by using the equivalent soil mass (ESM) approach, but with limited adoption. We evaluate the error in SOC stock assessment and change generated from fixed depth measurements over time relative to the ESM approach and propose a correction that can be readily adopted under current sampling and analytical methods. Our approach provides a more accurate estimate of SOC stock accumulation or loss that will help incentivize management practice changes that reduce the environmental impacts of agriculture and further legitimize the accounting practices used by the emerging carbon market and organizations that have pledged to reduce their supply chain greenhouse gas (GHG) footprints.

Tomography reconstruction of beams extracted from an ion source.

Commissioning of the CANREB (CANadian Rare isotope facility with Electron Beam ion source) system and its associated beamlines has recently begun at TRIUMF. At the head of this beamline is an ion source used to produce stable alkaline ions with energy up to 60 keV for the CANREB system. Throughout commissioning, it is essential to have a means of verifying beam quality and ensuring that the required beam parameters along the beamline are met. This is accomplished using tomography reconstruction, which consists of taking one-dimensional scans at different projections and reconstructing an image of the beam in two dimensions using the maximum entropy algorithm. Tomography enables the visualization of the shape of the beam as well as the investigation into the possible presence of aberrations. Initially, tomography reconstruction is performed by using simulated beam profiles at the measurement locations and is then performed by using measured beam profiles. Additionally, these measurements are benchmarked by fitting the initial beam parameters in our beam optics model, and the results are presented.

An electron beam ion trap and source for re-acceleration of rare-isotope ion beams at TRIUMF.

Electron beam driven ionization can produce highly charged ions (HCIs) in a few well-defined charge states. Ideal conditions for this are maximally focused electron beams and an extremely clean vacuum environment. A cryogenic electron beam ion trap fulfills these prerequisites and delivers very pure HCI beams. The Canadian rare isotope facility with electron beam ion source-electron beam ion sources developed at the Max-Planck-Institut für Kernphysik (MPIK) reaches already for a 5 keV electron beam and a current of 1 A with a density in excess of 5000 A/cm2 by means of a 6 T axial magnetic field. Within the trap, the beam quickly generates a dense HCI population, tightly confined by a space-charge potential of the order of 1 keV times the ionic charge state. Emitting HCI bunches of ≈107 ions at up to 100 Hz repetition rate, the device will charge-breed rare-isotope beams with the mass-over-charge ratio required for re-acceleration at the Advanced Rare IsotopE Laboratory (ARIEL) facility at TRIUMF. We present here its design and results from commissioning runs at MPIK, including X-ray diagnostics of the electron beam and charge-breeding process, as well as ion injection and HCI-extraction measurements.

Charge state breeding experiences and plans at TRIUMF.

At the Isotope Separation and ACceleration (ISAC) facility at TRIUMF, an electron cyclotron resonance ion source (ECRIS) has been set up for the charge state breeding of radioactive ions. In order to reduce background from stable ions generated in the ECRIS, several measures, including changing materials for the plasma chamber and the surrounding components, have been implemented. Further reduction has been achieved by using the post-accelerator chain as a mass filter. Since the implementation of those measures in 2013, physics experiments with accelerated radioactive isotopes of Rb, Sr, K, and Mg have been performed. In most cases, a charge breeding efficiency of several percent has been achieved. With the planned expansion of the isotope production capabilities at TRIUMF within the Advanced Rare IsotopE Laboratory project, two new target stations, one using photo-fission induced by a high-power electron beam at 50 MeV and the other one using 480 MeV protons as at ISAC, will be put into operation within the next 5 yr. Additionally, a new electron beam ion source (EBIS) based charge state breeding system will be installed. Background from such a source is expected to be much lower. The drawback is that for the efficient operation of such a system, pulsed beam operation is required, which makes the installation of an additional ion buncher in front of the EBIS necessary.

Ion source developments for the production of radioactive isotope beams at TRIUMF.

At the ISAC facility at TRIUMF radioactive ions are produced by bombarding solid targets with up to 100 µA of 500 MeV protons. The reaction products have to diffuse out of the hot target into an ion source. Normally, singly charged ions are extracted. They can be transported either directly to experiments or via an ECR charge state breeder to a post accelerator. Several different types of ion sources have to be used in order to deliver a large variety of rare isotope beams. At ISAC those are surface ion sources, forced electron beam arc discharge (FEBIAD) ion sources and resonant laser ionization sources. Recent development activities concentrated on increasing the selectivity for the ionization to suppress isobaric contamination in the beam. Therefore, a surface ion rejecting resonant laser ionization source (SIRLIS) has been developed to suppress ions from surface ionization. For the FEBIAD ion source a cold transfer line has been introduced to prevent less volatile components from reaching the ion source.

Recent developments of the ion sources at Tri University Meson Factory/Isotope Separator and ACcelerator Facility.

This paper describes the recent progresses concerning the on-line ion source at the Tri University Meson Factory/Isotope Separator and ACcelerator (TRIUMF/ISAC) Radioactive Ion-Beam Facility; description of the new design of the surface-ion-source for improved stability of the beam intensity, description of the transport path to the east target station at ISAC, description of the new brazing techniques that solved recurrent problems with water leaks on the target/ion source assembly in the vacuum system, finally, recent developments concerning the Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source are reported. In particular, a study on the effect of the plasma chamber volume on the ionization efficiency was completed.

Charge state breeding for the acceleration of radioactive ions at TRIUMF.

A 14.5 GHz electron cyclotron resonance ion source (PHOENIX from Pantechnik) has been set up at the Isotope Separation and ACceleration (ISAC) facility at TRIUMF for the charge state breeding of radioactive ions. After extensive testing and optimization on a test bench it has been moved on-line and put into operation. During a first test in 2008 a beam of (80)Rb(14+) was successfully created from (80)Rb(1+) and accelerated by the ISAC postaccelerator. Further tests with different stable and radioactive isotopes from the ISAC on-line sources and from a test source with stable Cs have been carried out. Until now an efficiency of 1.4% for (124)Cs(20+) has been obtained.

First Penning-trap mass measurement of the exotic halo nucleus 11Li.

In this Letter, we report a new mass for 11Li using the trapping experiment TITAN at TRIUMF's ISAC facility. This is by far the shortest-lived nuclide, t_{1/2}=8.8 ms, for which a mass measurement has ever been performed with a Penning trap. Combined with our mass measurements of ;{8,9}Li we derive a new two-neutron separation energy of 369.15(65) keV: a factor of 7 more precise than the best previous value. This new value is a critical ingredient for the determination of the halo charge radius from isotope-shift measurements. We also report results from state-of-the-art atomic-physics calculations using the new mass and extract a new charge radius for 11Li. This result is a remarkable confluence of nuclear and atomic physics.

Direct mass measurement of the four-neutron halo nuclide 8He.

A high-precision Penning trap mass measurement of the exotic 8He nuclide (T(1/2)=119 ms) has been carried out resulting in a reduction of the uncertainty of the halo binding energy by over an order of magnitude. The new mass, determined with a relative uncertainty of 9.2 x 10(-8) (deltam=690 eV) is 13 keV less bound than the previously accepted value. The mass measurement is of great relevance for the recent charge-radius measurement of 8He [P. Mueller, Phys. Rev. Lett. 99, 252501 (2007).10.1103/PhysRevLett.99.252501]. The 8He mass is the first result from the newly-commissioned Penning trap: TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) at the ISAC (Isotope Separator and Accelerator) radioactive beam facility at TRIUMF.

0(gs)+ -->2(1)+ transition strengths in 106Sn and 108Sn.

The reduced transition probabilities, B(E2; 0(gs)+ -->2(1)+), have been measured in the radioactive isotopes (108,106)Sn using subbarrier Coulomb excitation at the REX-ISOLDE facility at CERN. Deexcitation gamma rays were detected by the highly segmented MINIBALL Ge-detector array. The results, B(E2;0(gs)+ -->2(1)+)=0.222(19)e2b2 for 108Sn and B(E2; 0(gs)+-->2(1)+)=0.195(39)e2b2 for 106Sn were determined relative to a stable 58Ni target. The resulting B(E2) values are approximately 30% larger than shell-model predictions and deviate from the generalized seniority model. This experimental result may point towards a weakening of the N=Z=50 shell closure.

The ECRIS charge state breeding project at TRIUMF.

The performance of charge state breeding with an electron cyclotron resonance (ECR) ion source intended to increase the charge state of online produced radioactive ions at the ISAC facility at TRIUMF has been investigated. A 14 GHz PHOENIX from PANTECHNIK has been setup on a test bench. Singly charged ions have been produced with several ion sources typical for the on-line operation and were injected into the charge breeder. The main purpose of the tests has been the optimization of the efficiency for the charge breeding into the desired charge state. Maximum efficiencies reached so far with the standard one step deceleration of the ions in front of the plasma are up to about 6% for noble gas ions and about 3.5% for alkalines. As ion optics simulations show, the acceptance can be increased by a two step deceleration. In order to meet the velocity acceptance of the accelerator at different A/q values a similar two gap acceleration system for the highly charged ions has been installed to allow the source to run at different voltages. For the further beam transport to the accelerator, cross sections for charge exchange of the highly charged ions with the residual gas have been determined.

Off-line ion source terminal for ISAC at TRIUMF.

The off-line ion source (OLIS) terminal consists of a microwave cusp ion source, either a surface ion source or a hybrid surface-arc discharge ion source and an electrostatic switch that allows selecting any one of the sources without mechanical intervention. These sources provide variety of beams to ISAC experiments, for commissioning the accelerators, for setting up the radioactive experiments, and for tuning the beam lines. The microwave ion source has been operational since 1995 and provides singly and doubly charged beams from various stable isotopes for many ISAC experiments at high and low energy areas. Originally its prime goal was to provide beams from gaseous elements, but later two ovens and a sputtering system were added in order to provide beams from liquids and from solids. The surface ion source installed in 2002 can provide low energy spread beams from alkali and semialkali elements. It also has three separate ovens and an ionizer. Therefore, it can provide three different temperature regions simultaneously to provide different beams to ISAC. It is mainly used for laser spectroscopy experiments and other experiments, which require a finite beam quality. A hybrid surface-arc discharge ion source was also developed and installed in order to meet specific demands from experiments. This source terminal is now automated for start up and for mass selection. It is capable of providing stable beams for months without maintenance and it is also capable of providing negative ion beams if required. To date, over 40 different isotopes including many rear isotopes were delivered to various experiments from the OLIS source terminal. Performances of the ion sources and some of the results are discussed.

Coulomb excitation of neutron-rich Zn isotopes: first observation of the 2(1)+ state in 80Zn.

Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2(1)+ state in 78Zn could be firmly established and for the first time the 2+ --> 0(1)+ transition in 80Zn was observed at 1492(1) keV. B(E2,2(1)+ --> 0(1)+) values were extracted for (74,76,78,80)Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a good N=50 shell closure and a strong Z=28 proton core polarization. The new results serve as benchmarks to establish theoretical models, predicting the nuclear properties of the doubly magic nucleus 78Ni.

Coulomb excitation of 68,70Cu: first use of postaccelerated isomeric beams.

We report on the first low-energy Coulomb excitation measurements with radioactive Ipi=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon. Gamma rays were detected with the MINIBALL spectrometer. The 6- beam was used to study the multiplet of states (3-, 4-, 5-, 6-) arising from the pi2p3/2 nu 1g9/2 configuration. The 4- state of the multiplet was populated via Coulomb excitation and the B(E2;6--->4-) value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z=28 shell and N=40 subshell closures. A comparison with large-scale shell-model calculations using the 56Ni core shows the importance of the proton excitations across the Z=28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with N approximately 40.

Measurement of the sign of the spectroscopic quadrupole moment for the 2(1)+ state in 70Se: no evidence for oblate shape.

Using a method whereby molecular and atomic ions are independently selected, an isobarically pure beam of 70Se ions was postaccelerated to an energy of 206 MeV using REX-ISOLDE. Coulomb-excitation yields for states in the beam and target nuclei were deduced by recording deexcitation gamma rays in the highly segmented MINIBALL gamma-ray spectrometer in coincidence with scattered particles in a silicon detector. At these energies, the Coulomb-excitation yield for the first 2+ state is expected to be strongly sensitive to the sign of the spectroscopic quadrupole moment through the nuclear reorientation effect. Experimental evidence is presented here for a prolate shape for the first 2+ state in 70Se, reopening the question over whether there are, as reported earlier, deformed oblate shapes near to the ground state in the light selenium isotopes.

"Safe" Coulomb excitation of 30Mg.

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion."

Anaphylactic reactions to isosulfan blue dye during sentinel lymph node biopsy for breast cancer.

BACKGROUND: Sentinel lymph node biopsy (SLNB) is an alternative to axillary dissection for many breast cancer patients. Cases of anaphylactic reaction to the isosulfan blue dye used during SLNB have recently been reported. No study on the incidence of serious anaphylactic reactions during SLNB for breast cancer has been reported. METHODS: We reviewed 639 consecutive SLNBs for breast cancer performed at our institution. Sentinel lymph node biopsy was performed using both isosulfan blue dye and technetium-99m sulfur colloid. Cases of anaphylaxis were reviewed in detail. RESULTS: Overall, 1.1% of patients had severe anaphylactic reactions to isosulfan blue requiring vigorous resuscitation. No deaths or permanent disability occurred. In patients with anaphylaxis, hospital stay was prolonged by a mean of 1.6 days. In 1 patient, the anaphylactic reaction required termination of the operation. CONCLUSIONS: Prompt recognition and aggressive treatment of anaphylactic reactions to isosulfan blue are critical to prevent an adverse outcome. Lymphatic mapping with blue dye should be performed in a setting where personnel are trained to recognize and treat anaphylaxis.

Breast conservation therapy as a treatment option for the elderly. The M. D. Anderson experience.

BACKGROUND: Although almost half of all incidents of breast carcinoma occur in women age > or = 65 years, not enough is known about appropriate care for patients in this age group. The objective of the current study was to evaluate the role of breast conservation therapy in the management of breast carcinoma in women age > or = 65 years. METHODS: From 1970 to 1994, 1325 patients with carcinoma of the breast were treated with breast conservation therapy (segmental mastectomy and radiation therapy with or without axillary lymph node dissection) at The University of Texas M. D. Anderson Cancer Center. From this patient group, the authors identified 184 elderly women (> or = 65 years) with Stage 0-III disease at the time of diagnosis. RESULTS: The median patient age was 70 years (range, 65-88 years). The distribution of disease by stage among the women was Stage 0 disease in 12 patients (7%), Stage I disease in 107 patients (58%), Stage II disease in 63 patients (34%), and Stage III disease in 2 patients (1%). Comorbid conditions that may have influenced treatment planning were reported in 91 patients (50%). An axillary lymph node dissection was performed in 135 patients (73%), with positive axillary lymph nodes found in 30 patients (22%). Adjuvant chemotherapy was given to 10 patients (5%), and tamoxifen therapy was given to 63 patients (34%). Complications from treatment were reported in 24 patients (13%). With a median follow-up of 7.3 years (range, 0.25-23.5 years), 9 patients developed locoregional disease recurrence (5%), 10 patients developed contralateral breast carcinoma (5%), and 21 patients developed distant metastasis (11%). At last follow-up, 113 patients (61%) were alive, 15 patients (8%) were dead of disease, and 56 patients (30%) were dead of other causes. The 5-year and 10-year disease specific survival rates were 96% and 91%, respectively. CONCLUSIONS: Breast conservation therapy with segmental mastectomy and postoperative radiation therapy with or without axillary lymph node dissection provides excellent local control and disease free survival in elderly women with breast carcinoma. This treatment should be considered as the standard of care for elderly patients without severe comorbid disease.

Adverse prognostic significance of infraclavicular lymph nodes detected by ultrasonography in patients with locally advanced breast cancer.

BACKGROUND: Ultrasonography is increasingly used to evaluate the nodal status of breast cancer patients and specialized positioning permits assessment of the infraclavicular fossa. However, the incidence and significance of infraclavicular (level III) adenopathy detected sonographically in locally advanced breast cancer (LABC) has not been defined. METHODS: The study population consisted of 146 LABC patients registered in a prospective trial of induction chemotherapy between 1991 and 1996. All patients underwent ultrasound imaging before and after chemotherapy. Median follow-up was 32 months. RESULTS: Forty-two of 146 patients (29%) had suspicious infraclavicular adenopathy; all 42 had additional positive axillary lymph nodes by ultrasound. Disease-free and overall survival for the patients with suspicious infraclavicular adenopathy was significantly worse compared with patients without this feature; disease-free survival 50% versus 68% (P = 0.112); overall survival 58% versus 83% (P = 0.026). CONCLUSIONS: Nearly one third of LABC patients will have infraclavicular lymph node involvement by ultrasound imaging; this finding is a significant adverse prognostic feature, and we recommend that infraclavicular nodal evaluation become a routine component of the sonographic workup of breast cancer patients, particularly if lower axillary lymph nodes appear involved.