Prominent radiative contributions from multiply-excited states in laser-produced tin plasma for nanolithography.

Extreme ultraviolet (EUV) lithography is currently entering high-volume manufacturing to enable the continued miniaturization of semiconductor devices. The required EUV light, at 13.5 nm wavelength, is produced in a hot and dense laser-driven tin plasma. The atomic origins of this light are demonstrably poorly understood. Here we calculate detailed tin opacity spectra using the Los Alamos atomic physics suite ATOMIC and validate these calculations with experimental comparisons. Our key finding is that EUV light largely originates from transitions between multiply-excited states, and not from the singly-excited states decaying to the ground state as is the current paradigm. Moreover, we find that transitions between these multiply-excited states also contribute in the same narrow window around 13.5 nm as those originating from singly-excited states, and this striking property holds over a wide range of charge states. We thus reveal the doubly magic behavior of tin and the origins of the EUV light.

Systematic Study of L-Shell Opacity at Stellar Interior Temperatures.

The first systematic study of opacity dependence on atomic number at stellar interior temperatures is used to evaluate discrepancies between measured and modeled iron opacity [J. E. Bailey et al., Nature (London) 517, 56 (2015)NATUAS0028-083610.1038/nature14048]. High-temperature (>180 eV) chromium and nickel opacities are measured with ±6%-10% uncertainty, using the same methods employed in the previous iron experiments. The 10%-20% experiment reproducibility demonstrates experiment reliability. The overall model-data disagreements are smaller than for iron. However, the systematic study reveals shortcomings in models for density effects, excited states, and open L-shell configurations. The 30%-45% underestimate in the modeled quasicontinuum opacity at short wavelengths was observed only from iron and only at temperature above 180 eV. Thus, either opacity theories are missing physics that has nonmonotonic dependence on the number of bound electrons or there is an experimental flaw unique to the iron measurement at temperatures above 180 eV.

Collisional heating and adiabatic expansion of warm dense matter with intense relativistic electrons.

Adiabatic expansion of a warm dense Ti plasma has been observed after isochoric heating of a 100-µm-thick Ti foil with an ∼100-ns-long intense relativistic electron bunch at an energy of 19.8 MeV and a current of 1.7 kA. The expansion fits well with the analytical point-source solution. After 10 J is deposited and the plasma rapidly expands out of the warm dense phase, a stable degenerate plasma (T∼1.2eV) with n_{e}>10^{17}cm^{-3} is measured for >100 ns. This is the first temporal measurement of the generation and adiabatic expansion of a large volume (3×10^{-4}cm^{3}) of warm dense plasma isochorically heated by intense monochromatic electrons. The suite of diagnostics is presented, which includes time-resolved plasma plume expansion measurements on a single shot, visible spectroscopy measurements of the emission and absorption spectrum, measurements of the beam distribution, and plans for the future.

Electron impact ionization dynamics of para-benzoquinone.

Triple differential cross sections (TDCSs) for the electron impact ionization of the unresolved combination of the 4 highest occupied molecular orbitals (4b3g, 5b2u, 1b1g, and 2b3u) of para-benzoquinone are reported. These were obtained in an asymmetric coplanar geometry with the scattered electron being observed at the angles -7.5°, -10.0°, -12.5° and -15.0°. The experimental cross sections are compared to theoretical calculations performed at the molecular 3-body distorted wave level, with a marginal level of agreement between them being found. The character of the ionized orbitals, through calculated momentum profiles, provides some qualitative interpretation for the measured angular distributions of the TDCS.

Electron- and photon-impact ionization of furfural.

The He(i) photoelectron spectrum of furfural has been investigated, with its vibrational structure assigned for the first time. The ground and excited ionized states are assigned through ab initio calculations performed at the outer-valence Green's function level. Triple differential cross sections (TDCSs) for electron-impact ionization of the unresolved combination of the 4a″ + 21a' highest and next-highest occupied molecular orbitals have also been obtained. Experimental TDCSs are recorded in a combination of asymmetric coplanar and doubly symmetric coplanar kinematics. The experimental TDCSs are compared to theoretical calculations, obtained within a molecular 3-body distorted wave framework that employed either an orientation average or proper TDCS average. The proper average calculations suggest that they may resolve some of the discrepancies regarding the angular distributions of the TDCS, when compared to calculations employing the orbital average.

Nonlinear increase of X-ray intensities from thin foils irradiated with a 200 TW femtosecond laser.

We report, for the first time, that the energy of femtosecond optical laser pulses, E, with relativistic intensities I > 10(21) W/cm(2) is efficiently converted to X-ray radiation, which is emitted by "hot" electron component in collision-less processes and heats the solid density plasma periphery. As shown by direct high-resolution spectroscopic measurements X-ray radiation from plasma periphery exhibits unusual non-linear growth ~E(4-5) of its power. The non-linear power growth occurs far earlier than the known regime when the radiation reaction dominates particle motion (RDR). Nevertheless, the radiation is shown to dominate the kinetics of the plasma periphery, changing in this regime (now labeled RDKR) the physical picture of the laser plasma interaction. Although in the experiments reported here we demonstrated by observation of KK hollow ions that X-ray intensities in the keV range exceeds ~10(17) W/cm(2), there is no theoretical limit of the radiation power. Therefore, such powerful X-ray sources can produce and probe exotic material states with high densities and multiple inner-shell electron excitations even for higher Z elements. Femtosecond laser-produced plasmas may thus provide unique ultra-bright X-ray sources, for future studies of matter in extreme conditions, material science studies, and radiography of biological systems.

A higher-than-predicted measurement of iron opacity at solar interior temperatures.

Nearly a century ago it was recognized that radiation absorption by stellar matter controls the internal temperature profiles within stars. Laboratory opacity measurements, however, have never been performed at stellar interior conditions, introducing uncertainties in stellar models. A particular problem arose when refined photosphere spectral analysis led to reductions of 30-50 per cent in the inferred amounts of carbon, nitrogen and oxygen in the Sun. Standard solar models using the revised element abundances disagree with helioseismic observations that determine the internal solar structure using acoustic oscillations. This could be resolved if the true mean opacity for the solar interior matter were roughly 15 per cent higher than predicted, because increased opacity compensates for the decreased element abundances. Iron accounts for a quarter of the total opacity at the solar radiation/convection zone boundary. Here we report measurements of wavelength-resolved iron opacity at electron temperatures of 1.9-2.3 million kelvin and electron densities of (0.7-4.0) × 10(22) per cubic centimetre, conditions very similar to those in the solar region that affects the discrepancy the most: the radiation/convection zone boundary. The measured wavelength-dependent opacity is 30-400 per cent higher than predicted. This represents roughly half the change in the mean opacity needed to resolve the solar discrepancy, even though iron is only one of many elements that contribute to opacity.

The role of front-line anthracycline-containing chemotherapy regimens in peripheral T-cell lymphomas.

Peripheral T-cell lymphomas (PTCLs) are a heterogenous group of aggressive non-Hodgkin's lymphomas that are incurable in the majority of patients with current therapies. Outcomes associated with anthracycline-based therapies are suboptimal, but remain the standard of care for most patients, even though the benefits of this approach remain uncertain. This study retrospectively examined outcomes in a cohort of North American PTCL patients treated with both anthracycline- and nonanthracycline-containing regimens. The incorporation of anthracycline-containing regimens was associated with improved progression-free survival (PFS) and overall survival (OS). Patients treated with nonanthracycline-containing regimens were more likely to have high-risk features and were less likely to undergo high-dose therapy and stem cell transplantation. However, anthracycline use remained an independent predictor of improved PFS and OS when adjusting for these confounding variables. Anthracycline-based regimens and consolidation with high-dose therapy and autologous stem cell transplantation in appropriately selected patients remains a viable option for patients unable to participate in a clinical trial. Long-term disease-free survival is not optimal, highlighting the need for an improved understanding of disease pathogenesis, and the development of novel therapeutic strategies.

Ejection of quasi-free-electron pairs from the helium-atom ground state by single-photon absorption.

We investigate the single-photon double ionization of helium at photon energies of 440 and 800 eV. We observe doubly charged ions with close to zero momentum corresponding to electrons emitted back to back with equal energy. These slow ions are the unique fingerprint of an elusive quasifree photon double ionization mechanism predicted by Amusia et al. nearly four decades ago [J. Phys. B 8, 1248 (1975)]. It results from the nondipole part of the electromagnetic interaction. Our experimental data are supported by calculations performed using the convergent close-coupling and time-dependent close-coupling methods.

Bowel perforation in intestinal lymphoma: incidence and clinical features.

BACKGROUND: Perforation is a serious life-threatening complication of lymphomas involving the gastrointestinal (GI) tract. Although some perforations occur as the initial presentation of GI lymphoma, others occur after initiation of chemotherapy. To define the location and timing of perforation, a single-center study was carried out of all patients with GI lymphoma. PATIENTS AND METHODS: Between 1975 and 2012, 1062 patients were identified with biopsy-proven GI involvement with lymphoma. A retrospective chart review was undertaken to identify patients with gut perforation and to determine their clinicopathologic features. RESULTS: Nine percent (92 of 1062) of patients developed a perforation, of which 55% (51 of 92) occurred after chemotherapy. The median day of perforation after initiation of chemotherapy was 46 days (mean, 83 days; range, 2-298) and 44% of perforations occurred within the first 4 weeks of treatment. Diffuse large B-cell lymphoma (DLBCL) was the most common lymphoma associated with perforation (59%, 55 of 92). Compared with indolent B-cell lymphomas, the risk of perforation was higher with aggressive B-cell lymphomas (hazard ratio, HR = 6.31, P < 0.0001) or T-cell/other types (HR = 12.40, P < 0.0001). The small intestine was the most common site of perforation (59%). CONCLUSION: Perforation remains a significant complication of GI lymphomas and is more frequently associated with aggressive than indolent lymphomas. Supported in part by University of Iowa/Mayo Clinic SPORE CA97274 and the Predolin Foundation.

Peripheral blood absolute lymphocyte/monocyte ratio recovery during ABVD treatment cycles predicts clinical outcomes in classical Hodgkin lymphoma.

The peripheral blood absolute lymphocyte/monocyte count ratio at diagnosis (ALC/AMC-DX) predicts survival in classical Hodgkin lymphoma (cHL). However, a limitation of the ALC/AMC-DX is the inability to assess sequentially the host/tumor interaction during treatment. Therefore, we retrospectively examined the ALC/AMC ratio, as a surrogate marker of host immunity (ALC) and tumor microenvironment (AMC), at each adriamycin, bleomycin, vinblastine and dacarbazine treatment cycle as a predictor for clinical outcomes. From 1990 until 2008, 190 cHL patients were diagnosed, treated and followed at Mayo Clinic Rochester and qualified for the study. The ALC/AMC ratio at each treatment cycle was a predictor for overall survival (OS) and progression-free survival (PFS). An ALC/AMC ratio 1.1 versus ALC/AMC <1.1 during treatment cycles was an independent predictor for OS (hazard ratio (HR)=0.14; 95% confidence interval (CI): 0.04-0.40; P<0.0002) and for PFS (HR=0.19; 95% CI: 0.05-0.82; P<0.03). The ALC/AMC ratio during treatment cycles is a predictor for survival and provides a platform to develop therapeutic modalities to manipulate the ALC/AMC ratio during chemotherapy to improve clinical outcomes in cHL.

Evidence for a T-shape break-up pattern in the triple photoionization of Li.

We examine the angular distributions of all three electrons ionized from Li by a single photon near the triple ionization threshold using a fully quantum-mechanical treatment. We find strong evidence for a T-shape break-up pattern at a 5 eV excess energy as previously predicted by quasiclassical simulations [A. Emmanouilidou and J. M. Rost, J. Phys. B 39, 4037 (2006); A. Emmanouilidou, P. Wang, and J. M. Rost, Phys. Rev. Lett. 100, 063002 (2008)]. This finding is in conflict with the expected Wannier break-up dynamics of three electrons moving at mutual angles of 120°, which is expected to hold at energies a few eV above threshold. We use our quantum-mechanical approach to explore the physical mechanisms behind this unusual break-up configuration.

Exotic dense-matter states pumped by a relativistic laser plasma in the radiation-dominated regime.

In high-spectral resolution experiments with the petawatt Vulcan laser, strong x-ray radiation of KK hollow atoms (atoms without n = 1 electrons) from thin Al foils was observed at pulse intensities of 3 × 10(20) W/cm(2). The observations of spectra from these exotic states of matter are supported by detailed kinetics calculations, and are consistent with a picture in which an intense polychromatic x-ray field, formed from Thomson scattering and bremsstrahlung in the electrostatic fields at the target surface, drives the KK hollow atom production. We estimate that this x-ray field has an intensity of >5 × 10(18) W/cm(2) and is in the 3 keV range.

Strong molecular alignment dependence of H2 electron impact ionization dynamics.

Low-energy (E(0) = 54 eV) electron impact single ionization of molecular hydrogen (H(2)) has been investigated as a function of molecular alignment in order to benchmark recent theoretical predictions [Colgan et al., Phys. Rev. Lett. 101, 233201 (2008) and Al-Hagan et al., Nature Phys. 5, 59 (2009)]. In contrast to any previous work, we observe distinct alignment dependence of the (e,2e) cross sections in the perpendicular plane in good overall agreement with results from time-dependent close-coupling calculations. The cross section behavior can be consistently explained by a rescattering of the ejected electron in the molecular potential resulting in an effective focusing along the molecular axis.

Angular distributions for the complete photofragmentation of the Li atom.

We explore the complete breakup of the Li atom after absorption of a single photon, the purest example of the so-called four-body Coulomb problem. The resulting strongly correlated three-electron continuum is investigated by calculating the angular distributions of the ionized electrons using advanced close-coupling techniques. We find that the distributions are dominated by the Coulomb interactions between the electrons, that multiple break-up processes can be identified, and that the complex dynamics of the fragmentation process are evident for most scattering geometries.

The absolute monocyte and lymphocyte prognostic score predicts survival and identifies high-risk patients in diffuse large-B-cell lymphoma.

Despite the use of modern immunochemotherapy regimens, almost 50% of patients with diffuse large-B-cell lymphoma will relapse. Current prognostic models, including the International Prognostic Index, incorporate patient and tumor characteristics. In contrast, recent observations show that variables related to host adaptive immunity and the tumor microenvironment are significant prognostic variables in non-Hodgkin lymphoma. Therefore, we retrospectively examined the absolute monocyte and lymphocyte counts as prognostic variables in a cohort of 366 diffuse large-B-cell lymphoma patients who were treated between 1993 and 2007 and followed at a single institution. The absolute monocyte and lymphocyte counts in univariate analysis predicted progression-free and overall survival when analyzed as continuous and dichotomized variables. On multivariate analysis performed with factors included in the IPI, the absolute monocyte and lymphocyte counts remained independent predictors of progression-free and overall survival. Therefore, the absolute monocyte and lymphocyte counts were combined to generate a prognostic score that identified patients with an especially poor overall survival. This prognostic score was independent of the IPI and added to its ability to identify high-risk patients.

A phase II trial of the oral mTOR inhibitor everolimus in relapsed aggressive lymphoma.

The phosphatidylinositol 3-kinase signal transduction pathway members are often activated in tumor samples from patients with non-Hodgkin's lymphoma (NHL). Everolimus is an oral agent that targets the raptor mammalian target of rapamycin (mTORC1). The goal of this trial was to learn the antitumor activity and toxicity of single-agent everolimus in patients with relapsed/refractory aggressive NHL. Patients received everolimus 10 mg PO daily. Response was assessed after two and six cycles, and then every three cycles until progression. A total of 77 patients with a median age of 70 years were enrolled. Patients had received a median of three previous therapies and 32% had undergone previous transplant. The overall response rate (ORR) was 30% (95% confidence interval: 20-41%), with 20 patients achieving a partial remission and 3 a complete remission unconfirmed. The ORR in diffuse large B cell was 30% (14/47), 32% (6/19) in mantle cell and 38% (3/8) in follicular grade 3. The median duration of response was 5.7 months. Grade 3 or 4 anemia, neutropenia and thrombocytopenia occurred in 14, 18 and 38% of patients, respectively. Everolimus has single-agent activity in relapsed/refractory aggressive NHL and provides proof-of-concept that targeting the mTOR pathway is clinically relevant.

Lymphopenia assessed during routine follow-up after immunochemotherapy (R-CHOP) is a risk factor for predicting relapse in patients with diffuse large B-cell lymphoma.

A specific predictor during routine follow-up to ascertain risk for relapse after standard chemotherapy in non-Hodgkin's lymphoma (NHL) has not been identified. Thus, we studied absolute lymphocyte count (ALC) as a marker of poststandard chemotherapy (rituximab, cyclophosphamide, adriamycin, vincristine and prednisone (R-CHOP)) NHL relapse in patients with diffuse large B-cell lymphoma (DLBCL). ALC was obtained at the time of confirmed relapse and at last follow-up. From 2000 until 2006, 149 consecutive DLBCL patients, originally diagnosed, treated with R-CHOP and followed up at Mayo Clinic, Rochester, were included in this study. Patients at last follow-up without relapse (N=112) had a higher ALC compared with those with relapsed lymphoma ((N=37) median ALC x 10(9)/l of 1.43 (range: 0.33-4.0) versus 0.67 (range: 0.18-1.98), P<0.0001, respectively). ALC at the time of confirmed relapse was a strong predictor for relapse with an area under the curve =0.91 (P<0.0001). An ALC <0.96 x 10(9)/l at the time of confirmed relapse had a positive predictive value of 72% and a positive likelihood ratio of 7.4 to predict relapse after R-CHOP in DLBCL. Patients with an ALC>or=0.96 x 10(9)/l (N=103) had a cumulative incidence of relapse of 6 versus 79% with an ALC <0.96 x 10(9)/l (N=46) (P<0.0001). This study suggests that lymphopenia measured by ALC can be used as a marker to assess risk of DLBCL relapse during routine follow-up after standard chemotherapy.