Talk:China Jinping Underground Laboratory

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Reference material pending incorporation[edit]

June 5, 2015 conference, multiple papers[edit]

http://hep.tsinghua.edu.cn/CJPLNE/schedule2015.html 71.41.210.146 (talk) 05:30, 6 June 2015 (UTC)[reply]

Chinese-language source, any translators?[edit]

CHENG, Jian-Ping; WU, Shi-Yong; YUE, Qian; SHEN, Man-Bin (March 2011). 国际地下实验室发展综述 [A review of international underground laboratory developments]. Physics (in Chinese). 40 (3). Chinese Physical Society: 149–154. Abstract at http://www.wuli.ac.cn/EN/abstract/abstract31933.shtml

Abstract: Underground laboratories are essential for various important physics areas such as the search for dark matter,double beta decay, neutrino oscillation, and proton decay. At the same time, they are also a very important location for studying rock mechanics, earth structure evolution, and ecology. It is essential for a nation's basic research capability to construct and develop underground laboratories. In the past, China had no high-quality underground laboratory, in particular no deep underground laboratory, so her scientists could not work independently in major fields such as the search for dark matter, but had to collaborate with foreign scientists and share the space of foreign underground laboratories. In 2009, Tsinghua university collaborated with the Ertan Hydropower Development Company to construct an extremely deep underground laboratory, the first in China and currently the deepest in the world, in the Jinping traffic tunnel which was built to develop hydropower from the Yalong River in Sichuan province. This laboratory is named the China Jinping Underground Laborotory (CJPL) and formally opened on December 12, 2010. It is now a major independent platform in China and can host various leading basic research projects. We present a brief review of the development of various international underground laboratories, and especially describe CJPL in detail.

71.41.210.146 (talk) 08:09, 29 October 2015 (UTC)[reply]

Dear 71.41.210.146,
After you contacted me on my talk page, I had a read of the article. It is a bit repetitive, and a lot of the basic information has been incorporated into the article on CJPL already. On that note, however, there was a discrepancy in the dimensions of the main laboratory compared to the source cited in the article (ref. 16): according p. 153 of the paper, the dimensions of the main laboratory are 40m long, 6.5m wide, 7.5m high for a volume of 4000 m3, which conflicts with the dimensions in reference 16 (42m long, 6.5m wide, 6.5m high). Should the other sources be checked for what they state as the dimensions of the main laboratory?
Secondly, this fact from p. 154 may prove interesting, bearing in mind the relative age of the paper: "According to initial simulations and measurements, the cosmic ray flux of the China Jinping Underground Laboratory (CJPL) is around 100 cosmic rays per year per m2. Accurate cosmic ray influx data still requires measurements from experiments over a long period of time." Moreover, diagram 12 below that claims that CJPL receives the lowest penetration of cosmic rays of all of the world's underground laboratories.
Thirdly, this section somewhat conflicts with the information already in the article concerning the construction of the laboratory: "In January 2010, the excavation work of CJPL was completed. In June 2010, construction of its supporting projects was complete, and it smoothly went through review and acceptance. It marked the formal completion of the construction of China's first underground laboratory, and the world's most deeply covered by vertical rock." The article states that the excavation work at CJPL ended in May, but the month of completion of construction in the paper and the article are the same (June).
Finally, the paper then describes the first project at CJPL, CDEX: "In July 2010, the first dark matter experiment project at CJPL, China Darkmatter Experiment (CDEX), formally began the construction of its dark matter experiment shield, and in completed it in September 2010. On 12th December 2010, CJPL formally began operations. The CDEX group was the first to use CJPL, and began the installation and commissioning of its ultra-low energy threshold, pure germanium probe detector system, which was based on point-contact technology, for the project on the direct probing of dark matter." I am not a physicist so I am not sure if that last sentence makes sense, but perhaps this information is worth noting either here or on the CDEX page itself, since it is not present on either page.
I hope the quality of translation is all right, Chinese can seem a bit unwieldy when translated into English, and my approach is to be as literal as possible without being excessively repetitive. See my sandbox for the quotes in Chinese. I leave it to you to incorporate this information since my knowledge of the subject is meagre.

Ximenez Kin (talk) 20:36, 1 November 2015 (UTC)[reply]

Thank you very much! It doesn't look like there's much really novel there. I had hoped.
For dimensions, underground excavation can have some significant discrepancies between planned and achieved dimensions. Excavation can stop due to some difficulty, or a collapse can remove a bit more material than planned. So I'd be inclined to trust later sources as having measured numbers. I'm sure that's why they planned 40 m long and got 42 m. The other thing that's hard to account for, is lining. After excavation, the walls are lined with reinforced concrete, and sources are rarely clear on whether a dimension is to the raw rock or the usable interior space.
As for the lowest cosmic radiation, that's the second sentence in the lead of the CJPL article.
You're right that China Dark Matter Experiment article is just a stub and could use a lot of enhancement, but it does say "CDEX has p-type point-contact germanium detector surrounded by NaI(Tl) crystals, similar to the CoGeNT experiment.", which is pretty much the same except for the "ultra-low threshold" part. What is novel is the start date. Have to incorporate that!
One annoying conflict between sources is that the June 2010 construction completion date agrees with the current article, but the current source (reference 17,p.7) claims that excavation was "2009/7–2010/4", not January.
As for the translation, yes the drastically different styles of the two languages make it very difficult. The one thing that strikes me as odd is that you transcribe "Darkmater ［sic]", but I clearly see two "t"s in the original: "(China Darkmatter Experiment, CDEX)[14]".
71.41.210.146 (talk) 08:49, 2 November 2015 (UTC)[reply]

News stories from China[edit]

71.41.210.146 (talk) 03:40, 1 November 2015 (UTC)[reply]

2016 updates[edit]

71.41.210.146 (talk) 03:08, 21 July 2016 (UTC) Mostly about the Jinping Neutrino Experiment, but a bit about CJPL:[reply]

71.41.210.146 (talk) 13:23, 16 November 2016 (UTC)[reply]

Original research about CJPL-II expansion plans[edit]

Some clarifications I got via e-mail, so they're not citeable, but perhaps interesting to editors:

  • The bypass tunnels are dedicated to CJPL use; they are not needed for ongoing access to the water tunnels.
  • More exact numbers are 264,270 m3 existing tunnels and 130,591 m3 new excavation. The latter is the design value, of course; frequent collapses and rockbursts will change that.
  • The reason for the widening of the halls is that they don't think they need 1 m thick concrete on the walls any more.
  • There's no specific plan for the large power supply, but the scientists all thought it was a good idea just in case.
  • They have thought about cooling to go with the large power supply. The water flow in the drainage tunnel (which is 18 °C) varies from 8.5 m3/s in summer to 2.4 m3/s in winter. 10 MW heats water at a rate of 2400 kg·K/s. Thus, even at minimum flow, 10 MW would only heat the water by 1 °C.

71.41.210.146 (talk) 20:41, 18 August 2015 (UTC)[reply]

Snolab is much deeper than GranSasso[edit]

THe lab in the Sudbury Mine in Canada is already much deeper than the laboratory at Gran Sasso (6000 m.w.e see https://en.wikipedia.org/wiki/SNOLAB) So this sentence is wrong. The Jinping laboratory will be a strong competitor with Snolab

Thank you; I've clarified the statement. —swpbT 15:26, 13 January 2016 (UTC)[reply]
Thanks; I hadn't realized that was ambiguous. I'd rather put the comparison to SNOLAB somewhere other than the CJPL-II section, since the depth applies to CJPL-I just as well. (In fact, the final equivalent depth of CJPL-II hasn't been measured yet, although it will be close to CJPL-I.)
It's only the size that requires a detailed comparison with LNGS, since arguments can be made for either depending on how you choose to measure. I have to wrestle with the wording a bit. 71.41.210.146 (talk) 10:35, 29 January 2016 (UTC)[reply]
I took a stab at separating the comparisons. Listing both rival record-holders in one sentence just seems too crowded. I'm still not totally satisfied with it; further revision is invited. 71.41.210.146 (talk) 10:52, 29 January 2016 (UTC)[reply]

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Updated effective depth number[edit]

A recent re-analysis of the CJPL-1 muon flux:

quotes a significantly higher muon flux that the current citations in the article. Specifically, it claims (3.53±0.22stat.±0.07sys.)×10−10cm−2s−1, or 0.305±0.020 μ/m²/day. That's 50% higher than the earlier value of 0.2 μ/m²/day, and slightly higher than the 0.27 μ/m²/day figure normally used for SNOLAB, meaning that the two are tied rather than CJPL holding the record alone.

Any thoughts on how to update the text? One problem is getting a m.w.e. depth consistent with this value. Equation (4) from Mei and Hime

gives the following:

m.w.e. μ/cm2/s
6012.6 3.76×10−10
6056.7 3.53×10−10
6097.4 3.20×10−10
6141.7 3.125×10−10 (0.27 μ/m²/day)
6351.2 2.3148×10−10 (0.2 μ/m²/day)

Which doesn't match any of the published m.w.e. numbers I see, so perhaps I missed an update to that equation? 92.119.17.10 (talk) 17:40, 21 October 2020 (UTC)[reply]

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