This site uses cookies. By continuing to use this site you agree to our use of cookies. To find out more, see our Privacy and Cookies policy.
Skip to the content

Share this

Free weekly newswire

Sign up to receive all our latest news direct to your inbox.

Physics on film

100 Second Science Your scientific questions answered simply by specialists in less than 100 seconds.

Watch now

Bright Recruits

At all stages of your career – whether you're an undergraduate, graduate, researcher or industry professional – can help find the job for you.

Find your perfect job

Physics connect

Are you looking for a supplier? Physics Connect lists thousands of scientific companies, businesses, non-profit organizations, institutions and experts worldwide.

Start your search today


On top of the volcano – part two


By Matin Durrani at Sierra Negra, Mexico

Just as my Physics World colleague James Dacey mentioned earlier, neither of us felt super-wonderful yesterday visiting the Large Millimeter Telescope (LMT), which sits at a height of 4600 metres above sea level.  Spectacular though the facility is, the air pressure is roughly 60% of that at sea level and there is so little oxygen that even walking up a flight of stairs made me feeling pretty light-headed.

So, James and I were both quite glad to descend with LMT director David H Hughes to a height of 4100 metres, where it was time to visit another leading Mexican astronomy facility – the High-Altitude Water Cherenkov (HAWC) gamma-ray observatory.

Conditions here – despite being just 500 metres lower – are much more amenable and we were given a tour by Ibrahim Torres of the facility, which was officially opened in March this year. A collaboration between 26 Mexican and US institutions, HAWC consists of 300 detector tanks, which are each 4 m high, have a diameter of 7.3 m and are filled with 190,000 litres of extra-pure water.

Using four photomultiplier tubes in each tank, HAWC is designed to detect the “shower” of particles formed when high-energy cosmic rays strike the nuclei of gases in the Earth’s atmosphere. HAWC is expected to be 10–15 times more sensitive than its predecessor – the Milagro experiment in New Mexico.

HAWC is currently taking data, operating silently on the mountainside, with the only noise being the wind and the occasional truck bringing staff to the site. HAWC is not entirely isolated though: apparently rattlensakes, rabbits, lynx and the occasional coyote can be spotted or heard roaming around.

Find out more about HAWC in the video above, with Torres standing in the middle of the array. It looks quite a spooky place; in fact, part of a science-fiction movie has been shot here.

This entry was posted in Mexico visit 2015 and tagged , , , . Bookmark the permalink.
View all posts by this author  | View this author's profile


  1. M. Asghar

    The High-Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) seems to be a mini-Auger Observatory for high energy cosmic-rays installed and operational in Argentine for some years.

  2. Ibrahim

    We use the same technique but the main goal of HAWC is the study of gamma rays sources not cosmic rays, but we can detect them but the energy of the CR we got are not ultra high energy like auger

  3. Trackback: Blog -


  • Comments should be relevant to the article and not be used to promote your own work, products or services.
  • Please keep your comments brief (we recommend a maximum of 250 words).
  • We reserve the right to remove excessively long, inappropriate or offensive entries.

Show/hide formatting guidelines

Tag Description Example Output
<a> Hyperlink <a href="">google</a> google
<abbr> Abbreviation <abbr title="World Health Organisation" >WHO</abbr> WHO
<acronym> Acronym <acronym title="as soon as possible">ASAP</acronym> ASAP
<b> Bold <b>Some text</b> Some text
<blockquote> Quoted from another source <blockquote cite="">IOP</blockquote>
<cite> Cite <cite>Diagram 1</cite> Diagram 1
<del> Deleted text From this line<del datetime="2012-12-17"> this text was deleted</del> From this line this text was deleted
<em> Emphasized text In this line<em> this text was emphasised</em> In this line this text was emphasised
<i> Italic <i>Some text</i> Some text
<q> Quotation WWF goal is to build a future <q cite="">
where people live in harmony with nature and animals</q>
WWF goal is to build a future
where people live in harmony with nature and animals
<strike> Strike text <strike>Some text</strike> Some text
<strong> Stronger emphasis of text <strong>Some text</strong> Some text