Radioisotope production using lasers:From basic science to applications

The discovery of chirped pulse amplification has led to great improvements in laser technology,enabling energetic laser beams to be compressed to pulse durations of tens of femtoseconds and focused to a few micrometers.Protons with energies of tens of MeV can be accelerated using,for instance,target normal sheath acceleration and focused on secondary targets.Under such conditions,nuclear reactions can occur,with the production of radioisotopes suitable for medical application.The use of high-repetition lasers to produce such isotopes is competitive with conventional methods mostly based on accelerators.In this paper,we study the production of^(67)Cu,^(63)Zn,^(18)F,and^(11)C,which are currently used in positron emission tomography and other applications.At the same time,we study the reactions^(10)B(p,α)^(7)Be and^(70)Zn(p,4n)^(67)Ga to put further constraints on the proton distributions at different angles,as well as the reaction^(11)B(p,α)^(8)Be relevant for energy production.The experiment was performed at the 1 PW laser facility at VegaⅢin Salamanca,Spain.Angular distributions of radioisotopes in the forward(with respect to the laser direction)and backward directions were measured using a high purity germanium detector.Our results are in reasonable agreement with numerical estimates obtained following the approach of Kimura and Bonasera[Nucl.Instrum.Methods Phys.Res.,Sect.A 637,164–170(2011)].

Controlling the Cassie-to-Wenzel Transition: an Easy Route towards the Realization of Tridimensional Arrays of Biological Objects

In this paper we provide evidence that the Cassie-to-Wenzel transition, despite its detrimental effects on the wetting properties of superhydrophobic surfaces, can be exploited as an effective micro-fabrication strategy to obtain highly ordered arrays of biological objects. To this purpose we fabricated a patterned surface wetted in the Cassie state, where we deposited a droplet containing genomic DNA. We observed that, when the droplet wets the surface in the Cassie state, an array of DNA filaments pinned on the top edges between pillars is formed. Conversely, when the Cassie-to-Wenzel transition occurs, DNA can be pinned at different height between pillars. These results open the way to the realization of tridimensional arrays of biological objects.

The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources(Ⅱ)

Active galactic nuclei(AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type Ⅰ/Ⅱ(FRI/Ⅱ) radio galaxies. Following our previous work(Fan et al.), we present a sample of 2400 sources with measured radio flux densities of the core and extended components. The sample contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRⅡ galaxies and 104 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices, and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and spectral index exists for a large sample presented in this work.

Simulations of scattered neutrons for the time-of-flight enhanced diagnostics(TOFED)neutron spectrometer on EAST

The time-of-flight enhanced diagnostics(TOFED)neutron spectrometer has been installed in TOFED house,which is a newly-built neutron diagnostic lab outside the EAST experimental hall.The line of sight(LOS)of TOFED is defined by the collimator going through the 150 cm biological shielding wall,which can reduce background neutrons very effectively for the neutron spectral measurements.The Monte Carlo code MCNP5 is used in the simulations to characterize collimation effects and the radiation safety of the new house.The collimator makes neutron flux almost fully perpendicular to S 1 detectors.In addition,the proportion of scattered neutrons in the LOS of the TOFED is obtained for the measured spectral data interpretation.The simulation results show that the TOFED house satisfies the requirement for the TOFED operations at EAST and gives a safe environment for personnel access during the EAST operation.

Non-equilibrium Statistic Features in Dissipative Heavy Ion Collision ^(27)Al+ ^(27)Al

The excitation functions of dissipative products have been measured in the reaction 27Al+27Al at incident energies from 114 to 127MeV in steps of 200keV. Detection angles vary continuously from 10.4° to 57.4° in laboratory system. An angular coherent width more than 40° in center of mass is obtained. The results from the analysis of excitation functions with nonself-averaging are characterized by a quasi-periodic long-range energy structure embedded in the disorder Ericson fluctuation.

The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources(Ⅲ)

Active galactic nuclei(AGNs) can be divided into two major classes,namely radio-loud and radio-quiet AGNs.A small subset of the radio-loud AGNs is called blazars,which are believed to be unified with Fanaroff-Riley type Ⅰ and type Ⅱ(FRI&Ⅱ) radio galaxies.Following our previous work,we present a latest sample of 966 sources with measured radio flux densities of the core and extended components.The sample includes 83 BL Lacs,473 flat spectrum radio quasars,101 Seyferts,245 galaxies,52 FRIs&Ⅱs and12 unidentified sources.We then calculate the radio core-dominance parameters and spectral indices and study their relationship.Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources.We also confirm that the correlation between core-dominance parameter and radio spectral index extends over all the sources in a large sample presented.

Infrared synchrotron radiation spectroscopy and microspectroscopy: new tools for interdisciplinary applications

Synchrotron radiation sources, whose number is steadily increasing, are undoubtedly the most powerful and brilliant sources in the X-ray range. Although the synchrotron emission covers with high brilliance also the infrared region, its use in this energy range has developed at a much slower rate. Nowadays, after a couple of decades of attempts, the aim of extending the unique performances of the synchrotron source to the infrared domain is achieved by several dedicated beamlines in different countries. With their high-brilliance, polarized and broad-band radiation one may perform experiments that are out of the range of conventional sources from the near-IR up to the far-IR range.

The Way to Quench:Galaxy Evolution in A2142

We show how the star formation activity of galaxies is progressively inhibited from the outer region to the center of the massive cluster A2142.From an extended spectroscopic redshift survey of 2239 galaxies covering a circular area of radius~11 Mpc from the cluster center,we extract a sample of 333 galaxies with known stellar mass,star formation rate,and spectral index D_(n)4000.We use the Blooming Tree algorithm to identify the substructures of the cluster and separate the galaxy sample into substructure galaxies,halo galaxies,and outskirt galaxies.The substructure and halo galaxies are cluster members,whereas the outskirt galaxies are only weakly gravitationally bound to the cluster.For the cluster members,the star formation rate per stellar mass decreases with decreasing distance R from the cluster center.Similarly,the spectral index D_(n)4000 increases with R,indicating an increasing average age of the stellar population in galaxies closer to the cluster center.In addition,star formation in substructure galaxies is generally more active than in halo galaxies and less active than in outskirt galaxies,proving that substructures tend to slow down the transition between field galaxies and cluster galaxies.We finally show that most actively star-forming galaxies are within the cluster infall region,whereas most galaxies in the central region are quiescent.

Advances in nuclear detection and readout techniques

“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.

Radiative decays D*(s)→ D(s)γ in covariant confined quark model

Radiative decays D((s))*→D((s))γare revisited in light of new experimental data from the BaBar and BESⅢCollaborations.The radiative couplings gD*Dγencoding nonperturbative QCD effects are calculated in the framework of the covariant confined quark model developed by us.We compare our results with other theoretical studies and experimental data.The couplings(in GeV-1)|g(D*+D+γ)|=0.45(9)and|g(D*0D0γ)|=1.72(34)calculated in our model agree with the corresponding experimental data|g(D*+D+γ)|=0.47(7)and|g(D*0D0γ)|=1.77(16).The most interesting case is the decay Ds*→Dsγ,for which a recent prediction based on light-cone sum rules at next-to-leading order|gDs*Dsγ|=0.60(19)deviates from the first(and only to date)lattice QCD result|gDs*Dsγ|=0.11(2)at nearly3σ.Our calculation yields|gDs*Dsγ|=0.29(6),which falls somehow between the two mentioned results,although it is larger than those predicted in other studies using quark models or QCD sum rules.

Primordial black hole mass functions as a probe of cosmic origin

We discuss a novel window to probe the origin of our universe via the mass functions of primordial black holes(PBHs).The mass functions of PBHs are simply estimated using the conventional Press-Schechter formalism for two paradigms of cosmic origin,including inflationaryΛCDM and bounce cosmology.The standard inflationaryΛCDM model cannot generate an appreciable number of massive PBHs;however,non-trivial inflation models with blue-tilted power spectra at small scales and matter bounce cosmology provide formation mechanisms for heavy PBHs,which in turn,may seed the observed supermassive black holes(SMBHs).By fitting the SMBH mass functions at high redshift(z~6)derived from Sloan Digital Sky Survey(SDSS)and Canada-France High-z Quasar Survey(CFHQS)quasars,for two paradigms of cosmic origin,we derive constraints on the PBH density fraction fPBHat z~6 and the characteristic mass M_(★),with the prior assumption that all SMBHs stem from PBHs.We demonstrate that this newly proposed procedure,relying on astronomical measurements that utilize deep-field surveys of SMBHs at high redshift,can be used to constrain models of cosmic origin.Additionally,although not the main focus of this paper,we evolve the mass function from z~6 to z~0 through an assumption of 3×10^(8)-year Eddington’s accretion,and give a rough estimation of fPBHat z~0.

地震前后电离层截止频率处电场频谱强度变化分析--以2006年汤加MW8.0地震为例

以汤加MW8.0地震为例,着重分析了DEMETER卫星记录中截止频率附近电磁场频谱在震前的异常演化特征.根据地震前后该区域3个月的数据对比,发现电场频谱增强与地震孕育的关系很不明显.而长时间、大范围的电场频谱减弱现象可能更值得关注,白天和夜间的电场频谱显示同一特征.2006年夏秋季节38次6级以上强震短期异常的统计平均结果显示,白天的电场频谱在震前24小时距离震中2 000 km左右可能有一定增强,达到背景值的3倍均方差.但其它时段多以下降为主,而夜间无论震前震后比较明显的超过3σ的异常均以下降为主.最后讨论了地震-电离层异常孕育耦合机理.

黄光激光用Dy,Tb∶LuAG透明陶瓷的制备与性能研究

以NH_(4)HCO_(3)为沉淀剂,通过共沉淀法合成了分散性良好的Dy,Tb∶LuAG纳米粉体,并研究了前驱体的热分解行为、粉体的物相及显微形貌。在不添加任何烧结助剂的情况下,采用真空预烧结合热等静压烧结技术首次制备出高透明的Dy,Tb∶LuAG陶瓷,并研究了预烧温度对陶瓷显微形貌及光学质量的影响。当预烧温度为1600℃时,退火后的Dy,Tb∶LuAG陶瓷(厚度为1.5 mm)在578 nm处的直线透过率达到83.6%,平均晶粒尺寸为0.9μm。此外,退火后的3%Dy,1%Tb∶LuAG透明陶瓷在447 nm的吸收截面积为1.3×10^(-21) cm^(2),半高宽为3.0 nm,与商用GaN蓝色激光二极管具有良好的匹配性。研究表明,Dy,Tb∶LuAG透明陶瓷在黄光激光领域具有潜在的应用价值。

一种稳定磁场的方法

本文叙述了HERMES横向极化气体靶的外磁场的磁感应强度随时间减弱现象的发现,探讨了这种减弱的原因。由此开发了一种全自动补偿系统。利用该系统后,磁场的稳定度得到很大提高,如在某测量位置,预置磁感应强度为338.6mT的磁场的稳定度由原来的±0.45mT变化幅度改善到±0.004mT(Stat)±0.048(Syst)mT。

ALB上焦耳热场的形态分布特征及环境意义探讨

利用地磁场MAGSAT(1980 )模型计算了软流圈—岩石圈边界 (ALB)上的焦耳热场 ,分析了它的形态分布特征 ,并探讨了其环境意义。发现ALB上焦耳热高值中心的分布与全球地热带和火山的分布有较好的一致性 ,焦耳热的水平尺度与地热涡的水平尺度、我国大陆上多雨带的间距及降水量和气温的高相关带的间距相当。低纬地带ALB上焦耳热中心的分布与全球平均年最大降水量中心的分布特征有很好的对应。另外 ,ALB上全球最大焦耳热中心位于我国青藏高原东南部的热点上。最后 ,讨论了地磁与气候的可能联系。

固体激光用Nd:Lu_(2)O_(3)透明陶瓷的制备和光学性能研究

Nd:Lu_(2)O_(3)材料由于具有高热导率、低声子能量和优异的光学特性而成为非常有前景的高功率固体激光器用的增益介质。但Lu_(2)O_(3)单晶的熔点超过2400℃,难以生长,而Lu_(2)O_(3)陶瓷既能在低温下制备,又具有与晶体相当的光学性质和激光性能从而备受关注。本研究制备了高透明的Nd:Lu_(2)O_(3)陶瓷并对其光学性质和激光性能进行探究。以共沉淀法制备的纳米粉体为原料,采用真空烧结结合热等静压(HIP)两步烧结法制备了1.0at%Nd:Lu_(2)O_(3)透明陶瓷。对制备的粉体、素坯和陶瓷的微结构进行了表征:HIP后处理的陶瓷平均晶粒尺寸是724.2nm。厚度为1.0mm的1.0at%Nd:Lu_(2)O_(3)透明陶瓷在1100 nm处的直线透过率是82.4%,样品在806 nm处的吸收截面为1.50×10^(-20)cm^(2),而根据荧光光谱计算得到的发射截面为6.5×10^(–20)cm^(2)。分别在878.8和895.6 nm波长激发下,1.0at%Nd:Lu_(2)O_(3)透明陶瓷(4)^F3/2→(4)^I11/2跃迁的平均荧光寿命均为169ms。当输出耦合镜的透过率TOC=2.0%时,退火后的1.0at%Nd:Lu_(2)O_(3)透明陶瓷获得了最大输出功率为0.47 W的准连续(QCW)激光输出,斜率效率为8.7%。本研究成功制备了显微结构均匀、高透明度的1.0at%Nd:Lu_(2)O_(3)陶瓷,并展示了其在固体激光增益介质领域的广阔应用潜力。

共沉淀纳米粉体制备Yb:CaF2激光陶瓷及其性能研究（英文）

利用共沉淀法合成的粉体,通过真空烧结结合热压烧结后处理制备了掺镱的氟化钙透明陶瓷(Yb:CaF2)。在600℃预烧1 h,700℃热压烧结2 h制备的5at%Yb:CaF2透明陶瓷在1200 nm处的直线透射率达到92.0%。对陶瓷的显微结构、光谱特性和激光性能进行了测试和讨论。研究结果表明,陶瓷样品的显微结构均匀,平均晶粒尺寸为360 nm。此外,计算得到Yb:CaF2陶瓷在977nm处的吸收截面和1030nm处的发射截面分别为0.39×10–20和0.26×10–20cm2。最后,对Yb:CaF2陶瓷激光性能进行了表征,得到最大输出功率为0.9 W,最大斜率效率为23.6%。

Changes in cellular mechanical properties during onset or progression of colorectal cancer

Colorectal cancer(CRC) development represents a multistep process starting with specific mutations that affect proto-oncogenes and tumour suppressor genes.These mutations confer a selective growth advantage to colonic epithelial cells that form first dysplastic crypts, and then malignant tumours and metastases. All these steps are accompanied by deep mechanical changes at the cellular and the tissue level. A growing consensus is emerging that such modifications are not merely a byproduct of the malignant progression, but they could play a relevant role in the cancer onset and accelerate its progression. In this review, we focus on recent studies investigating the role of the biomechanical signals in the initiation and the development of CRC. We show that mechanical cues might contribute to early phases of the tumour initiation by controlling the Wnt pathway, one of most important regulators of cell proliferation in various systems. We highlight how physical stimuli may be involved in the differentiation of non-invasive cells into metastatic variants and how metastatic cells modify their mechanical properties, both stiffness and adhesion, to survive the mechanical stress associated with intravasation, circulation and extravasation. A deep comprehension of these mechanical modifications may help scientist to define novel molecular targets for the cure of CRC.

DmpIRFs and DmpST:DAMPE instrument response functions and science tools for gamma-ray data analysis

Observing GeV gamma-rays is an important goal of the DArk Matter Particle Explorer(DAMPE)for indirect dark matter searching and high energy astrophysics. In this work, we present a set of accurate instrument response functions for DAMPE(DmpIRFs) including the effective area, point-spread function and energy dispersion, which are crucial for gamma-ray data analysis based on statistics from simulation data. A dedicated software named DmpST is developed to facilitate the scientific analyses of DAMPE gamma-ray data. Considering the limited number of photons and angular resolution of DAMPE, the maximum likelihood method is adopted in DmpST to better disentangle different source components. The basic mathematics and framework regarding this software are also introduced in this paper.