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China Jinping underground laboratory (CJPL) is located in the Jinping Mountain, Sichuan Province, southwest China, with a rock overburden of about 2400m, and it is currently the deepest underground laboratory in the world, and will become one of the largest with the completion of its extension project (CJPL-II). Based on CJPL-II, the Deep Undergrou...
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... The Jinping neutrino experiment (JNE) 1 is the next-generation solar neutrino experiment at the China Jinping Underground Laboratory (CJPL) with a rock overburden of approximately 2,400 meters. 2 As with other neutrino detectors, 3-7 the JNE will install photomultiplier tubes (PMTs) to detect the photons emitted during particle interactions with matter and determine the particle's energy, position, and direction. Due to the extremely low probability of neutrinos interacting with matter, an ultralow background environment is essential to detect rare neutrino signals, including solar neutrinos, 8 geoneutrinos, 9 supernova neutrinos, 10 and neutrinoless double beta decay. ...
The Jinping Neutrino Experiment (JNE) will utilize approximately 3000 8-inch MCP-PMTs identified as GDB-6082 from North Night Vision Technology to detect neutrinos. To enhance the effective coverage of the JNE detector, mounting a custom-designed light concentrator on each photomultiplier tube (PMT) is a practical and economical approach. We measured angular responses of the concentration factor at four wavelengths in air medium for the concentrator with the selected cutoff angle of 70 degree. The measurements align with the Monte Carlo simulations. Furthermore, our results indicate that these concentrators can improve the efficiency of light collection by 40 % under parallel illumination conditions. However, this enhancement results in a slight increase in transit-time spread, with the full width at half maximum (FWHM) increasing by less than 0.3 ns. We conclude that the developed light concentrators are highly suitable for the JNE.
... PandaX 和 JUNA 等实验组在 CJPL 开展暗物质直接 探测、 无中微子双贝塔衰变和核天体物理等研究工作 [7] 。 CJPL 分为一期(CJPL-I)和二期(CJPL-II) ， 其中 CJPL-I 于 2010 年底投入运行， 可用空间约 4000 m 3 。CJPL-II 将实验室空间拓展到 30,0000 m 3 ，共有 A1 至 D2 共 8 个实验大厅(图 1) 。依托二期的实验 空间，建设了国家重大科技基础设施"极深地下极低 本底前沿物理实验设施" (简称锦屏大设施) ， 使 CJPL 成为世界上岩石埋深最深、 宇宙线通量最低和可用空 间最大的深地实验室 [8] [14] ，由固定在不同位置的 152 Eu、 137 Cs 和 60 Co 放射源刻度得到 [15] ，实验刻度数据以及拟合 结果见图 2。f(E,θ)将用于 2.3.1 节环境材料中放射性 核素转化系数的计算。 图 2 探测器角响应：测量数据(蓝色叉号)、不同天顶角 下拟合曲线(红色线)和二维插值曲面(灰色面) Figure 2 The detector angular response: the experimental data (blue marks), the fitting curves of f(E, θ) (θ=0, 10,...,90) (red lines) and the 2D interpolating surface (gray surface) Page 3 of 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 [15] : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 As one of the National Major Science and Technology Infrastructure Construction Projects of China, the Deep Underground and ultra-low Radiation Background Facility for frontier physics experiments (DURF) is built based on the phase II of China Jinping underground laboratory (CJPL). During its construction, various techniques, including low-radioactivity material screening and multi-layer waterproof radon-resistant layers, were implemented to control the radioactivity background in the laboratory. ...
... The radioactivity from the experimental hall is shielded by the water to a negligible level. The radioactivity of the water was measured during the PandaX-4T operation to be ∼10 µBq/kg for 238 U, 232 Th, 40 K, and 222 Rn, leading also to a negligible background contribution [59,60]. We plan to instrument the water shielding with two layers of 8-inch PMTs, separated by Tyvek foil as optical reflectors. ...
We propose a major upgrade to the existing PandaX-4T experiment at the China Jinping Underground Laboratory. The new experiment, PandaX-xT, will be a multi-ten-tonne liquid xenon, ultra-low background, and general-purpose observatory. The full-scaled PandaX-xT contains a 43-t liquid xenon active target. Such an experiment will significantly advance our fundamental understanding of particle physics and astrophysics. The sensitivity of dark matter direct detection will be improved by nearly two orders of magnitude compared to the current best limits, approaching the so-called “neutrino floor” for a dark matter mass above 10 GeV/c2, providing a key test to the Weakly Interacting Massive Particle paradigm. By searching for the neutrinoless double beta decay of 136Xe isotope in the detector, the effective Majorana neutrino mass can be measured to a 10–41 meV/c2 sensitivity, providing a key test to the Dirac/Majorana nature of neutrinos. Astrophysical neutrinos and other ultra-rare interactions can also be measured and searched for with an unprecedented background level, opening up new windows of discovery. Depending on the findings, PandaX-xT will seek the next stage upgrade utilizing isotopic separation of natural xenon.
... The CDEX collaboration has given its first 0νββ limit of T 0ν 1=2 > 6.4 × 10 22 yr for a p-type point contact high-purity germanium detector [23]. A next-generation 0νββ experiment CDEX-300ν has been proposed in CJPL-II [24]. The CDEX-300ν experiment aims at achieving a discovery potential that reaches the inverted-ordering neutrino mass scale region with 1-ton yr exposure. ...
A natural broad energy germanium detector is operated in the China Jinping Underground Laboratory for a feasibility study of building the next generation experiment of the neutrinoless double-beta (0νββ) decay of 76 Ge. The setup of the prototype facility, characteristics of the broad energy germanium detector, background reduction methods, and data analysis are described in this paper. A background index of 6.4 × 10 −3 counts=ðkeV kg dayÞ is achieved and 1.86 times lower than our previous result of the CDEX-1 detector. No signal is observed with an exposure of 186.4 kg day, thus a limit on the half life of 76 Ge 0νββ decay is set at T 0ν 1=2 > 5.62 × 10 22 yr at 90% C.L. The limit corresponds to an effective Majorana neutrino mass in the range of 4.6-10.3 eV, dependent on the nuclear matrix elements.
... The CDEX collaboration has given its first 0νββ limit of T 0ν 1=2 > 6.4 × 10 22 yr for a p-type point contact high-purity germanium detector [23]. A next-generation 0νββ experiment CDEX-300ν has been proposed in CJPL-II [24]. The CDEX-300ν experiment aims at achieving a discovery potential that reaches the inverted-ordering neutrino mass scale region with 1-ton yr exposure. ...
A natural broad energy germanium detector is operated in the China Jinping Underground Laboratory for a feasibility study of building the next generation experiment of the neutrinoless double-beta (0νββ) decay of Ge76. The setup of the prototype facility, characteristics of the broad energy germanium detector, background reduction methods, and data analysis are described in this paper. A background index of 6.4×10−3 counts/(keV kg day) is achieved and 1.86 times lower than our previous result of the CDEX-1 detector. No signal is observed with an exposure of 186.4 kg day, thus a limit on the half life of Ge76 0νββ decay is set at T1/20ν>5.62×1022 yr at 90% C.L. The limit corresponds to an effective Majorana neutrino mass in the range of 4.6–10.3 eV, dependent on the nuclear matrix elements.
... Both the current CDEX and Panda-X experiments, together with associated low background counting facilities and a data acquisition system, are located within CJPL Hall A, a 2,000 m 3 room of approximate dimensions 40 m (length) x 6.5 m (width) x 6.5 m (height), see Fig. 1, from Yue and Wong (2013) and Li (2013a). The total volume of CJPL-I for physics is ~ 4,000 m 3 , including access to the Hall A. JPL-I construction started in 2009. ...
... The total volume of CJPL-I for physics is ~ 4,000 m 3 , including access to the Hall A. JPL-I construction started in 2009. The laboratory opened on 12 December 2010, as described by Li (2013a) The Ya Long River in Sichuan province makes a big U-turn around JinPing mountain. The JinPing tunnels were excavated to connect two hydropower houses constructed into opposing sides of the mountain before and after the Uturn, in order to exploit the difference in river water levels, over the length of the tunnels, to generate electric power. ...
... Marble rock samples collected in JinPing tunnels and in CJPL contain relatively low concentrations of K, Th, and radium. The measurement are 40 K < 1.1 Bq/kg, 226 Ra (609 keV) 1.8 ± 0.2 Bq/kg, and 232 Th (911 keV) < 0.27 Bq/kg, as reported by Li (2013a) and Chen (2012). The potassium and thorium upper bounds correspond to concentrations of less than 10 ppm and 67 ppb, respectively. ...
During 2013-2015 an expansion of the China JinPing underground Laboratory
(CJPL) will be undertaken along a main branch of a bypass tunnel in the JinPing
tunnel complex. This second phase of CJPL will increase laboratory space to
approximately 96,000 m^3, which can be compared to the existing CJPL-I volume
of 4,000 m^3. One design configuration has eight additional hall spaces, each
over 60 m long and approximately 12 m in width, with overburdens of about 2.4
km of rock, oriented parallel to and away from the main water transport and
auto traffic tunnels. Concurrent with the excavation activities, planning is
underway for dark matter and other rare-event detectors, as well as for
geophysics/engineering and other coupled multi-disciplinary sensors. In the
town meeting on 8 September, 2013 at Asilomar, CA, associated with the 13th
International Conference on Topics in Astroparticle and Underground Physics
(TAUP), presentations and panel discussions addressed plans for one-ton
expansions of the current CJPL germanium detector array of the China Darkmatter
EXperiment (CDEX) collaboration and of the duel-phase xenon detector of the
Panda-X collaboration, as well as possible new detector initiatives for dark
matter studies, low-energy solar neutrino detection, neutrinoless double beta
searches, and geoneutrinos. JinPing was also discussed as a site for a
low-energy nuclear astrophysics accelerator. Geophysics/engineering
opportunities include acoustic and micro-seismic monitoring of rock bursts
during and after excavation, coupled-process in situ measurements, local,
regional, and global monitoring of seismically induced radon emission, and
electromagnetic signals.
Direct detection of light-mass dark matter is a frontier topic in international physics research. The reduction of system threshold is important in order to improve the sensitivity of light-mass dark matter detection. The scientific goal of the China Dark Matter Experiment (CDEX) at Jinping Underground Laboratory in China is to detect WIMPs utilizing a high-purity germanium array detector. CDEX-10 achieved the most sensitive results in the 4 to 5 GeV/ c ² range. CDEX-50 aims to achieve an energy threshold of 100 eV, which significantly increases data bandwidth and complicates the implementation of noise reduction algorithms, thereby posing challenges to the readout electronics system. In this paper, a triggerless readout electronics system based on FPGA-GPU is designed for CDEX-50, which can achieve full energy range detection from 100 eV to 10 MeV. A verification prototype of a triggerless electronics system utilizing a Broad Energy Germanium (BEGe) detector has been developed to test the performance of high-bandwidth transmission and data processing. The results demonstrate that the bit error rate for the high-speed transmission link of the triggerless readout electronics system is below 10 ¹⁵ . Furthermore, the FPGA-GPU transmission bandwidth, utilizing P2P DMA, achieves 100.2 Gbps, and the mean filter implemented on the GPU is capable of processing a 64 Gbps data stream in real-time. These results provide foundation for the design of the triggerless readout electronics system for CDEX-50.
