Wireless Network Requirements and Solutions for the Future Circular Collider:A Hostile Indoor Environment

The European organization for nuclear research(CERN)is planning a high performance particle collider by 2050,which will update the currently used Large Hadron Collider(LHC).The design of the new experiment facility includes the definition of a suitable communication infrastructure to support the future needs of scientists.The huge amount of data collected by the measurement devices call for a data rate of at least 1 Gb/s per node,while the need of timely control of instruments requires a low latency of the order of 0.01μs.Moreover,the main tunnel will be 100 km long,and will need appropriate coverage for voice and data traffic,in a special underground environment subject also to strong radiations.Reliable voice,data and video transmission in a tunnel of this length is necessary to ensure timely and localized intervention,reducing access time.In addition,using wireless communication for voice,control and data acquisition of accelerator technical systems could lead to a significant reduction in cabling costs,installation times and maintenance efforts.The communication infrastructure of the Future Circular Collider(FCC)tunnel must be able to circumvent the problems of radioactivity,omnipresent in the tunnel.Current technologies transceivers cannot transmit in such a severely radioactive environment.This is due to the immediate destruction of any active or passive equipment by radioactivity.The scope of this paper is to determine the feasibility of robust wireless transmission in an underground radioactive tunnel environment.The network infrastructure design to meet the demand will be introduced,and the performance of different wireless technologies will be evaluated.

An <i>e</i>⁺<i>e</i>^-/<i>γγ</i>/<i>ep</i>Accelerator Complex at a Future Circular Collider

This is the second paper by the author describing versatile accelerator complexes that could be built at a Future Circular Collider (FCC) in order to produce e+e-, γγ and ep collisions. The facility described here features an ILC-based e+e- collider placed tangentially to the FCC tunnel. If the collider is positioned asymmetrically with respect to the FCC tunnel, electron (or positron) bunches could be accelerated by both linacs before they are brought into collision with the 50-TeV beams from the FCC proton storage ring (FCC-pp). The two linacs may also form a part of the injector chain for FCC-pp. The facility could be converted into a γγ collider or a source of multi-MW beams for fixed-target experiments.

Explanation of the Hidden Variables in the Electron-Positron Annihilation Process in Terms of the Quantum Entanglement and the Conservation of Flux Quantum

We show that the electron-positron annihilation process resulting with the creation of two gamma photons cannot be fully determined without the conservation of the angular momentum which has two elements, namely, the conservation of the spin angular momentum and the conservation of the quantum flux which work as the conservation of the magnetic moments as well. The conservation of the quantum flux has never been considered so far for any collision process. We show that the missing conservation rule in the above process is the conservation of the total quantum flux which is the hidden variable of that process. By using the quantum entanglement together with the conservation of the quantum flux we show that the initial and the final states of this collision are fully determined. We also show that each of the gamma photons created in the end carries a quantum flux of &plusmn;&Phi;=&plusmn;hc/e?with itself along the propagation direction. Here the (+) and (&minus;) signs correspond to the right hand and left circular helicity, respectively.

环形正负电子对撞机注入引出分布参数型冲击磁铁设计

环形正负电子对撞机(CEPC)是一台周长100 km,最高能量为120 GeV的双环对撞机。为了满足不同能量粒子从增强器注入到对撞环,针对W和Z能量模式设计了对撞环离轴注入系统,用于实现束流的累积。为了提高注入效率,兼容不同注入能量,不同束流填充模式,同时尽可能减少注入过程中冲击磁铁对其它束团的扰动,要求对撞环离轴注入冲击磁铁系统是一个上升时间和下降时间小于200 ns,脉冲底宽调节范围为440~2420 ns的梯形波脉冲放电系统。和常见的集中参数型冲击磁铁相比,分布参数型冲击磁铁具有更优越的动态响应特性,适合产生一个前沿更加陡峭、波形更为理想的梯形波脉冲。根据CEPC的束流注入物理需求,完成了一台分布参数型冲击磁铁的物理设计和结构设计,并采用了PSpice和Opera程序进行模拟仿真。设计结果表明:冲击磁铁由26级LC单元结构叠装而成,磁铁总长为1018 mm,磁有效长度为942 mm;在[−20,20]mm磁铁孔径内,磁场强度为0.0421 T,磁场均匀性优于±0.2%;冲击磁铁系统总上升时间(10%~90%)为193 ns,下降时间(90%~10%)为191 ns。理论分析、PSpice程序和Opera程序模拟均验证了磁铁设计方案的可行性。

争议性科学事件中科学家间争论焦点研究

爆发于科学共同体成员之间的争论在进入公众视野后,争论焦点由认知要素向社会要素过渡,呈现出复杂的问题情境。为了厘清公共科学争论中持有不同观点的科学家群体的争论焦点,对王贻芳与杨振宁二人关于大型环形加速器−环形正负电子对撞机−超级质子对撞机(CEPC-SPPC)的争议性科学事件展开个案研究。根据编码数据梳理出双方争论的焦点是平等观念和经济问题,并对围绕上述焦点的科学话语展开文本分析。研究发现,在公共科学争论中,科学共同体成员之间争论的焦点本质是对多元主体利益的不同衡量方式,这种不同恰又体现为科学共同体成员能否超出科学共同体的立场来思考科学决策。

Method study of parameter choice for a circular proton–proton collider

In this paper we show a systematic method of appropriate parameter choice for a circular proton-proton collider by using an analytical expression for the beam beam tune shift limit, starting from a given design goal and technical limitations. A suitable parameter space has been explored. Based on the parameter scan, sets of appropriate parameters designed for a 50 km and 100 km circular proton proton collider are proposed.

Importance of heavy quark longitudinal structure function measurements at future circular collider energies

In this article,we consider the ratio of structure functions for heavy quark pair production at low values of.The importance of this ratio for charm and beauty pair production is examined according to the Hadron Electron Ring Accelerator(HERA)data.The behavior of these ratios is considered due to the hard pomeron behavior of the gluon distribution function.The results are in good agreement with the HERA data.Expanding this data to the range of new energies underscores the importance of these measurements for heavy quarks.The ratio of charm and beauty structure functions at the proposed Large Hadron electron Collider(LHeC)is considered as a function of invariant center-of-mass energy.For top pair production this ratio is extracted with known kinematics of the LHeC and Future Circular Collider electron-hadron(FCC-eh)colliders.Comparison of the results obtained for the ratio of top structure functions in LHeC and FCC-eh are proportional to the specified inelasticity range.

探究物质最基本的结构——从中微子和正负电子对撞谈起

首先对粒子物理的基本目标、实验方法、研究现状以及粒子标准模型进行了简要介绍。解释了为何寻求超出标准模型的物理信号是现阶段物理学研究的核心任务。接着着重介绍了首个在粒子物理实验中被证实的超出标准模型的实验信号、中微子振荡及其实验测量,以及通向新物理原理的探针——希格斯(Higgs)玻色子。最后,介绍了高能物理实验设施,特别是现有的北京正负电子对撞机项目和未来的环形正负电子对撞机项目。对于后者,除了明晰其突出的物理学意义和物理学性能,还阐述了其对科学技术的促进作用。

Design and high-power test of 800-kW UHF klystron for CEPC

To reduce the energy demand and operation cost for circular electron positron collider(CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-k W continuous wave(CW) klystron operating at frequency of 650-MHz has been designed. The results of beam–wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional(3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed.When the gun operated at DC voltage of 80 k V and current of 15.4 A, the klystron peak power reached 804 k W with output efficiency of about 65.3% at 40% duty cycle. The 1-d B bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation.

基于微波-电子康普顿背散射的环形正负电子对撞机束流能量测量方案

环形正负电子对撞机(CEPC)束流能量的精确标定是希格斯粒子质量宽度、W/Z玻色子质量的精确测量,从而精确检验标准模型的基本实验依据.基于此,束流能量的误差控制要求在10-5水平.康普顿背散射方法是适用于百GeV高能电子对撞机束流能量高精度标定的测量方法.本文拟采用微波电子康普顿背散射后对散射光子能量的精确测量,来反推CEPC束流能量,理论预计精度可达到3 MeV左右.首先根据设计需求选定圆波导传输TM_(01)模微波,并求解该条件下的电磁场分布情况及坡印廷矢量.根据波导内光子分布传输情况提出设计思路简化计算的复杂程度,结合高纯锗探测器灵敏度、同步辐射本底等限制条件联立方程求解符合设计要求的参数.使用最优的一组波导内径、微波波长、电子入射角数据求得微波功率为100 W时的微分散射截面对能量的导数及对撞亮度,进一步求得15 MeV能量的散射光子数密度,根据该能量下同步辐射光子数密度的大小分析了信噪比.理论上论证了该方案的可行性并讨论了该方案有待进一步研究的技术难点与问题.

Light dark sector searches at low-energy high-luminosity e^＋e^- colliders

Although the standard model （SM） is extremely successful, there are various motivations for considering the physics beyond the SM. For example, the SM includes neither dark energy nor dark matter, which has been confirmed through astrophysical observations. Examination of the dark sector, which contains new, light, weakly-coupled particles at the GeV scale or lower, is well motivated by both theory and dark-matter detection experiments. In this mini-review, we focus on one particular case in which these new particles can interact with SM particles through a kinematic mixing term be- tween U（1） gauge bosons. The magnitude of the mixing can be parameterized by a parameter e. Following a brief overview of the relevant motivations and the constraints determined from numerous experiments, we focus on the light dark sector phenomenology at low-energy high-luminosity e^＋e^- colliders. These colliders are ideal for probing the new light particles, because of their large production rates and capacity for precise resonance reconstruction. Depending on the details of a given model, the typical observed signatures may also contain multi lepton pairs, displaced vertices, and/or missing energy. Through the use of extremely large data samples from existing experiments, such as KLOE, CLEO, BABAR, Belle, and BESIII, the ε 〈 10^-4-10^-3 constraint can be obtained. Obviously, future experiments with larger datasets will provide opportunities for the discovery of new particles in the dark sector, or for stricter upper limits on ε. Once the light dark sector is confirmed, the particle physics landscape will be changed significantly.

Canonical Angular Momentum of Electron, Positron and the Gamma Photon

We calculate the canonical angular momentum of a free electron, positron and gamma photon. We show that for any particle with charge q the canonical angular momentum (Jc) is written as the summation of the kinetic angular momentum (Jkin) and the intrinsic quantum flux dependent terms. In terms of the z-components this can be written as . For a free electron (e-) and a positron (e+) depending on the spin orientation we find that:;;and respectively. Similarly for a gamma (γ) photon, propagating in z direction with an angular frequency ω, the canonical angular momentum is found to be: , here the (+) and (-) signs stand for the right and left hand circular helicity respectively.

Searching for the light leptophilic gauge boson Zx via four-lepton final states at the CEPC

We investigate the possibility of detecting the leptophilic gauge boson Z_(x) predicted by the U(1)Le−Lμmodel via the processes e+e−→ℓ^(+)ℓ^(−)Z_(x)(Z_(x)→ℓ^(+)ℓ^(−))and e+e−→ℓ^(+)ℓ^(−)Z_(x)(Z_(x)→νℓ¯νℓ)at the Circular Electron Positron Collider(CEPC)with a center of mass energy√s=240 GeV and luminosity L=5.6ab^(−1).We provide the expected sensitivities of the CEPC to the parameter space at the 1σ,2σ,3σ,and 5σlevels.

Positivity in electron-positron scattering:testing the axiomatic quantum field theory principles and probing the existence of UV states

We consider the positivity bounds on dimension-8 four-electron operators and study two related phenomenological aspects at future lepton colliders.First,if positivity is violated,probing such violations will revolutionize our understanding of the fundamental pillars of quantum field theory and the S-matrix theory.We observe that positivity violation at scales of 1-10 TeV can potentially be probed at future lepton colliders even if one assumes that dimension-6 operators are also present.Second,the positive nature of the dimension-8 parameter space often allows us to either directly infer the existence of UV-scale particles together with their quantum numbers or exclude them up to certain scales in a model-independent way.In particular,dimension-8 positivity plays an important role in the test of the Standard Model.If no deviations from the Standard Model are observed,it allows for simultaneous exclusion limits on all kinds of potential UV-complete models.Unlike the dimension-6 case,these limits apply regardless of the UV model setup and cannot be removed by possible cancellations among various UV contributions.This thus consists of a novel and universal test to confirm the Standard Model.We demonstrate with realistic examples how all the previously mentioned possibilities,including the test of positivity violation,can be achieved.Hence,we provide an important motivation for studying dimension-8 operators more comprehensively.

Quantum electrodynamics experiments with colliding petawatt laser pulses

A new generation of high power laser facilities will provide laser pulses with extremely high powers of 10 petawatt(PW)and even 100 PW, capable of reaching intensities of 1023 W/cm^2 in the laser focus. These ultra-high intensities are nevertheless lower than the Schwinger intensity IS= 2.3×1029 W/cm^2 at which the theory of quantum electrodynamics(QED) predicts that a large part of the energy of the laser photons will be transformed to hard Gamma-ray photons and even to matter, via electron–positron pair production. To enable the investigation of this physics at the intensities achievable with the next generation of high power laser facilities, an approach involving the interaction of two colliding PW laser pulses is being adopted. Theoretical simulations predict strong QED effects with colliding laser pulses of 10 PW focused to intensities 10^(22) W/cm^2.

Measurement of the effective weak mixing angle at the CEPC

We present a study of the measurement of the effective weak mixing angle parameter(sin^(2)θ^(l)_(eff))at the Circular Electron Positron Collider(CEPC).As a fundamental physics parameter,sin^(2)θ_(eff)^(l) plays a key role not only in the global test of the standard model electroweak sector,but also in constraining the potential beyond standard model new physics at the high energy frontier.CEPC proposes a two year running period around the Z boson mass pole at high instataneous luminosity,providing a large data sample with 4 × 10^(12)Z candidates generated in total.It allows a high precision measurement of sin^(2)θ^(l)_(eff) both in the lepton and quark final states,where the uncertainty can be one order of magnitude lower than any previous measurement at the LEP,SLC,Tevatron,and LHC.It will improve the overall precision of the sin^(2)θ^(l)_(eff) experimental determination to be comparable to the preicision of the theoretical calculation with two-loop radiative corrections,and it will also provide direct comparisons between different final states.In this paper,we also study the measurement of sin^(2)θ^(l)_(eff) in the high mass region.Taking data for one month,the precision of sin^(2)θ^(l)_(eff) measured at 130 GeV from b quark final state is 0.00010,which will be an important experimental observation on the energy-running effect of sin^(2)θ^(l)_(eff).

2018年,亚洲希格斯玻色子工厂的里程碑之年

2012年7月4日,粒子物理科学家们在欧洲核子研究中心（CERN）的大型强子对撞机（LHC）上发现了标准模型中的基石性粒子——希格斯粒子.希格斯玻色子的发现为人类进一步深入研究物质深层次问题打开了新的大门.希格斯玻色子既是标准模型的基石,同时也是其他谜团产生的主要原因,如自然性问题、质量层次问题和真空稳定问题等.因此,对希格斯玻色子的精确测量,可以很好地探索标准模型和标准模型超越之外的深层次物理理论问题.

认真总结我国大科学工程艰辛历程和成功经验,加快推进我国高能物理大科学工程的顺利实施

新中国成立70年来,我国在国防、科学、技术、工业、经济、社会等方面取得了举世瞩目的发展.回顾和总结我国独特的发展历史和成功经验,对我国实现党中央制定的"两个一百年"战略规划具有重要意义,对我国制定和实施"十四五"及之后长远发展计划具有重要意义.自20世纪50年代起,我国充分发挥顶层布局设计和决策机制及举国体制的优越性,从顶层布局设计上抓住"两弹一星"和核潜艇等军事科学技术工程这一龙头,打下了我国在基础研究、科学技术、工业体系、人才培养和国际合作等方面的坚实基础.

欧洲核子中心汇聚全球的努力筹划未来的巨大环型对撞机

结合2014年2月参加"对未来环型对撞机研究的启动会议"的见闻,介绍了全球高能物理界正在讨论如何通过广泛国际合作、在欧洲核子中心(CERN)建造未来环形高能加速器和粒子对撞机的新动态,简要回顾了历史上高能加速器和对撞机建设的经验和教训,摘编了与会者提出的相关见解和建议,希望中国高能物理的长远发展可从中借鉴和参考。

Study of CEPC performance with different collision energies and geometric layouts

The Circular Electron-Positron CoUider （CEPC） is one of the largest projects planned for high energy physics in China. It would serve first as a Higgs factory and then upgrade to a hadron collider. In this paper we give the 50 km and 100 km design for both single ring and double ring schemes, including Z boson, W boson and Higgs boson, by using an optimized method. Also, we give the potential of CEPC running at the Z and W poles. We analyse the relationship of luminosity with circumference and filling factor, which gives a way to evaluate the choice of geometry, and compare the nominal performances of CEPC-SPPC, LHC and FCC.