Valuable Secrets For Increasing Traffic To Your Blog

blog secretGetting visitors and increasing traffic to your blog is practically the most important thing to do if you’re planning to make any money or generate interest about your writing. Let’s see what are some secrets you can use to get your blog to 1000+ visitors everyday.

 

Secret #1  Unique content – content is King

Blogs that are unique in terms of content and are regularly updated will generate more visitors. Content that is instructive, engaging and relevant will bring in more repeat visitors and also allow you to rank high in search engines. 

Another important thing is to keep the content simple and easy to understand. Make sure you arrange the content in such a way that it’s easily accessed – using categories and also keywords is a great way to do this.

 

Secret #2  Article marketing

When you are attempting to expand your blog movement compose articles and submit them to different sites, for example, “ezinearticles.com” for instance. Ensure that when you present your article you incorporate the connection to your blog to pull in the visitor. These links are great for  SEO as it builds keywords for your blog. The better the article is the more traffic that you can produce to your blog so be imaginative and take as much time as is needed.

Don’t simply make a rushed article and submit it, in light of the fact that on the off chance that it is not pertinent to your website, odds are the traffic will not flow to your blog.

Secret #3 Search engine optimization

You have to make a rundown of key words that you need to use in your blog. This is particularly for your title as it is the primary thing that the web search tool webcrawlers will analyze at first. A decent practice for any blog is around a 5% or less keyword density. You can likewise do some examination on some competitors websites to perceive what watchwords they are utilizing to get traffic.

Secret #4 Social Sites

Promote your websites on social sites. This is an awesome approach to create activity. When you consider the number of social sites there are out there think about how much traffic that will drive to your blog.

Secret #5 Post Regularly

One of your most important tasks as a blog owner is to post to your blog on a regular basis. This is a practice that will help you with both the search engines and your visitors. But there has to be some value to the content; posting low quality, rehashed or duplicate content isn’t going to be helpful. You have to deliver high caliber content as well as keeping your blog regularly updated. A study of various blogs will reveal that the top blogs are usually updated daily, while ones that receive little traffic only publish new posts once in a while. It’s not necessary to be constantly updating your blog; if possible, however, you should try to do it daily.

Secret #6 The Importance of Community

If you can build a real feeling of community around your blog, you’ll find it easier to get traffic. The more connected your readers feel to your blog, the more likely it is that they’ll come back often, which is something you definitely want. A communal feeling is the reason social networks are so popular, and you can take advantage of this principle. Although there are many metrics to measure the performance of a blog, having a vibrant community is the best way to find out its overall success. Community building is the way you make your visitors feel at home on your blog so they have a good reason to come back frequently.

These strategies (not so secret anymore  🙂 ) for getting more traffic to your blog are simple to use and very effective, but they do require consistent effort.

Do This 3 Things Before Even Thinking About Article Marketing!

We all know what wonders article directories can do with the right technique and also proper planning, but alas there are still tons of people out there who are clueless. Low quality articles, writing styles that are downright annoying and not marketing the articles all make up the deadly sins of the article marketing world.

But What Is Article Marketing?!

Simply put it’s the act of making articles work for you as marketing agents – either by driving more traffic to your site, influencing readers to buy something, generating more followers etc. Your article gets read and it sets in motion activities that are designed to provide benefit to you, and also the reader of course.

OKAY…So Tell Me How?

Article directories – sites that allows authors to freely post articles about a wide range of topics or categories. You write a high quality article about a topic or subject of your expertise, and submit it to the article directories. Article directories help your articles with exposure, better visibility to search engines and a huge reader base, and help drive traffic back to your site – when done properly.

When deciding on which article directory you would like to submit to, please do your homework and select it based on the following principles:

 

  1. Relevance – if you’re marketing SEO services, Google for sites that make the best sense and impact
  2. Demographics – this is tricky but take time to research and assess if the demographics targeted are a fit for your articles
  3. Services you are offering – try to post to article directories which have a healthy, steady stream of articles pertaining to your topic or subject matter

 

  1. PREPARE, PLAN & STRATEGIZE

Consider your end goal in writing or submitting the article – research keywords, utilize proper SEO tactics (keyword density, keyword relevance, semantics, links etc) and determine your strategy. Don’t be afraid to change your articles in terms of paragraph placements, grammar, approach (critical, review, informational) and test what works best for you.

This step also involves making a list of article directories which best suit your purpose.

  1. WRITING

List out the key ideas, keywords and general notes – then get to actually writing the article. It’s a good idea to limit the article length to around 500 words. If you can’t write, outsource it but ensure you properly edit or manage the process to get quality articles.

 

  1. MARKETING

The final step is submitting the articles to the article directories you chose earlier. Don’t submit a whole bunch at one time, 1 to 2 will be a good bet. Also make sure that the link that points back to your website allows you to track the source. It’s recommended to do this so you know exactly which article directory works and which does not.

 

And that’s it folks. I hope this article will help you write great articles and bring about success in your journey in the world of article marketing.

How to make viral articles!

Do you have a site however experiencing difficulties attracting readers or visitors? Don’t you wish you could simply kick back and let another person do the hard work of attracting traffic for you? Well you can! Furthermore, they’ll do it for you for FREE.

Truth is stranger than fiction, we’re not discussing paid promoting here. What we’re discussing works superior to paid publicizing and doesn’t cost you a thing! We’re discussing article entries.

    Presenting an article to an article registry is an incredible method for creating activity for your site, regardless of whether you’re quite recently beginning or simply attempting to expand the movement to your site.

You should simply compose an article that would be helpful to your prospects, and put an asset box toward the finish of the article with a connection to your site. An asset box is only a little explanation about yourself with a connection to your site for them to discover more data. At that point you submit it to a couple article registries. That is it. Other individuals assume control starting here.

So what precisely happens when you post articles on an article index? Well your article gets posted on their site. A ton of other site proprietors check these article catalogs for articles they can use as substance for their site or pamphlet. Be that as it may, when they utilize your article, they consent to not change the article and to leave YOUR asset box on it. They publicize your site for you! You don’t need to do anything.

I can hear you now, this all sounds incredible yet I’m not that good at composing articles. Well you don’t need to be! You’re not attempting to offer a novel here. All you are doing is composing something that you think would be valuable for another person to know. For whatever length of time that it is useful I’m certain there will be a lot of individuals who WANT to read it. Furthermore, the more you compose, the better your written work will get. So don’t lounge around hesitating on the grounds that you don’t feel you can compose sufficient. Get it done. You’ll improve.

This looks great yet is it truly superior to anything paid promoting? I would state yes and there are a few explanations behind this. Above all else it is FREE. Second, it’s viral. Investigate this situation. On the off chance that you post an article on a couple article registries and just 10 individuals choose to utilize it in their pamphlet. Each of these individuals has 2,000 individuals on their rundown. This promotes your site to 20,000 individuals. Presently envision if 100 individuals utilized your article or on the off chance that they had 20,000 individuals each on their rundown. This stuff is effective. Third, it builds up you as a specialist in that field. Individuals will put stock in you progressively and will be all the more eager to by your item in the event that you’ve effectively given them helpful data. Forward, after you’ve composed a considerable measure of article you can arrange them into your own particular digital book and give it away for nothing (with connections to your site obviously) or offer it. Paid promoting doesn’t measure up to this. Try not to squander any additional time. Begin composing articles now!

An Introduction To Drop Shipping The Easy Way To Start An Ebay Business

 

The term ‘Drop shipping’ has turned into a mainstream strategy for offering merchandise on eBay. This strategy permits the merchant on eBay to pitch merchandise without the need a stock or the need to dispatch the products. Many organizations additionally permit the client to buy their merchandise and after that have them daze drop send the item to the triumphant bidder. The organization utilizes the eBay vender’s name or organization points of interest as the arrival deliver to make it give the idea that the thing really originated from them and not the genuine merchandise provider. The genuine provider will be that as it may, handle the bundling, the transportation, and any arrival of things.

It is anything but difficult to begin a drop shipping business on eBay. You don’t have to make any tremendous speculations when beginning your ebay drop shipping business and your underlying expenses will be insignificant. Keep in mind this is a virtual business and does not require overwhelming startup costs, not at all like a disconnected business that can costly to begin.

Drop shipping has picked up in notoriety since you don’t need to pay for and stock the forthright. Once the purchaser makes the installment, the request is sent to the drop shipper and they finish the method including sending the following number for the shipment, which is then sent to the purchaser – You don’t pay until you have sold the thing! This strategy guarantees that you procure cash and the dangers are limited for the vendors.

In any case, ensure that you find true blue drop shippers to work with and maintain a strategic distance from the “brokers” that can bring about issues with transportation and your benefits. Avoid drop deliver guides that simply list organizations and locations. These aides do not have any substance and, in the event that you need to discover “agents” you won’t have to look any further. A decent hotspot for discovering your optimal drop dispatch organization is at alibaba.com.

Ebay is the greatest internet business entry on the planet today and is giving a job to a huge number of individuals around the world. As indicated by a study by AC Nielsen in 2005, 724,000 Americans have affirmed that their work relies on upon their closeout ebay site store. Aside from this number, in any event another 1.5 million individuals have said that they make an additional salary by offering their items on e-cove. A year ago 150 million enlisted clients sold their items on eBay and exchanges added up to over $34 billion. This makes e-narrows the greatest online commercial center comprehensively.

You needn’t bother with any unique aptitudes for beginning a drop shipping business on eBay and despite the fact that there are sure items that you can’t offer on a closeout ebay web based shopping store, you can offer for all intents and purposes whatever else and bear in mind that you will have a current database of more than 150 million clients to pitch your item to. You will in any case, need to painstakingly evaluate the advantages and disadvantages to guarantee achievement, read as much as you can regarding the matter and gain from those that know. A decent asset can be found here.

Ebay gets something close to 1.5 billion page audits each month. You can envision subsequently the sort of activity that can visit your sale ebay site store – simply make sure to look at what is offering and what isn’t before you begin and simply recollect this, a little time and exertion is all that will be required to begin and after that simply kick back and watch the offering. Indeed, even while you are resting, on vacation or doing whatever else, ebay is as yet working for you, day and night.

Successful Website Flipping Business

Site flipping isn’t just the act of buying and selling websites, but it’s an actual business that takes time to learn and takes hard work if one hopes to become successful. The three tips below should help you make more with your site flipping business.

The best tip you will ever learn about site flipping is to make sure you will actually make money off of your websites. If you want to make as much money as possible for your site, make sure you are making money from your site. Some people put their sites up to be sold merely because those sites get a lot of visitors, but this is the wrong way to go.

If your website is making lots of money, you will have no troubles selling it quickly. Your website should always sell for the amount it’s worth, but you will have to decrease your prices if your website is only getting traffic that is not bringing in any money. After all, you’re doing a business here and you would want your efforts to pay off. So the more money your site makes, the better it will be.

For best results, be patient and give your site time to build revenue so that you can have an even better site. Just always keep in mind that you will have to provide the past six months revenue data for your websites in your auction ads.

It’s a great idea to make some real world contacts with other people in the industry. This is one business where having the right contacts can go far. Make lists of buyers that that have bought sites from you in the past and always send them an email now and again. Chances are that if they’ve bought from you a single time, they’ll want your sites again. Not only that, but having solid contacts means you can partner up with some of those contacts if you ever find that a site takes a huge investment to build or buy. Great contacts are a good idea in all forms of business, not just site flipping, let’s be honest.

Lastly, set your goals before you commence your business so that you know which way to go. In other words, you need to make up your mind when it comes to how much income you’re expecting, the types of sites you want to deal with, and whether or not you are looking for shorter or longer term flips. So the more clear you are in these areas, the better will be your results. In short, site flipping can make you tons of profit, so if you haven’t started flipping websites, there’s no better time to get started.

Want some great ideas on which sites generate the most money $$$ when flipped? Click here and we will send you our super exclusive list!

The Neutrino Chronicles -There is no Ghost Particle?

Despite multiple years of efforts to track the elusive ghost particle, we are no closer to detecting the actual ghost particle, the magical neutrino. Recent news from the scientific world seems to suggest that the LHC scientists have not seen the particle. Physicists looking for the other flavor of ghost particles have also not made any progress.

The ghost particle has been talked about in theory for over 50 years, but it was only in the last 30 years or so that our technology has advanced enough to allow scientists to build the detectors, the most famous one being the Large Hadron Collider (LHC). Earlier this week, physicists at the IceCube Neutrino Observatory said they failed to turn up any evidence of a sterile neutrino. This is disappointing, but first let’s talk about what these things are.

Neutrinos are a type of subatomic particle, like electrons or quarks, but they are especially misanthropic. They constantly speed through Earth, and through you, and through everything, interacting with everything else so minimally that you would never notice.

They have no mass, which has made detection impossible so far but we’re still trying to detect them as they hold the key to the formation of the universe, and also the secrets of dark matter apart from why there is a universe. Somehow, at the very beginning of time, matter and antimatter got divided up unevenly, leading to an excess of matter — the reason we are all here. Some theorists think neutrinos could have played a role in this.

Neutrino

  • Muon
  • Electron
  • Tau

Neutrino Detection

Neutrino Detection

We can only detect the presence of a neutrino in our experiment if it interacts. Neutrinos interact in two ways:

  • charged-current interactions, where the neutrino converts into the equivalent charged lepton (e.g. inverse beta decay, νe + p → n + e+) – the experiment detects the charged lepton;
  • neutral-current interactions, where the neutrino remains a neutrino, but transfers energy and momentum to whatever it interacted with – we detect this energy transfer, either because the target recoils (e.g. neutrino-electron scattering, ν + e → ν + e) or because it breaks up (e.g. 2H + ν → p + n + ν).

Charged-current interactions occur through the exchange of a W±particle, neutral-current through the exchange of a Z0.

In principle, charged-current interactions are easier to work with, because electrons and muons have characteristic signatures in particle detectors and are thus fairly easy to identify. They also have the advantage that they “flavour-tag” the neutrino: if an electron is produced, it came from an electron-neutrino. However, there must be enough available energy to allow the mass of the lepton to be created from E = mc2 – this means that for very low-energy neutrinos (e.g. solar and reactor neutrinos) charged-current interactions are only possible for electron-neutrinos.

Various different detector technologies have been used in neutrino experiments over the years, depending on the requirements of the particular study. Desirable features of a neutrino experiment will typically include several of the following:

  • low energy threshold, so that low-energy neutrinos can be detected and studied (especially for solar neutrinos);
  • good angular resolution, so that the direction of the detected particle can be accurately reconstructed (especially for astrophysical neutrinos);
  • good particle identification, so that electrons and muons can be well separated (essential for oscillation experiments);
  • good energy measurement, so that the energy of the neutrino can be reconstructed (useful for oscillation measurements and astrophysics);
  • good time resolution, so that the time evolution of transient signals can be studied (essential for supernova neutrinos, and important for other astrophysical sources);
  • charge identification, so that leptons and antileptons can be separated (will be essential for neutrino factory experiments).

It is not possible to have all of these things in one experiment – for example, experiments with very low energy threshold tend not to have good angular or energy resolution. Neutrino physicists will select the most appropriate technology for the aims of their particular experiment.

Radiochemical experiments

The lowest energy thresholds are provided by radiochemical experiments, in which the neutrino is captured by an atom which then (through inverse beta decay, a charged-current interaction) converts into another element. The classic example of this is the chlorine solar neutrino experiment. Even lower thresholds were achieved by using gallium as the target: the reaction 71Ga + ν → 71Ge + e has a threshold of only 0.233 MeV, and is even sensitive to pp neutrinos (see figure 6). The produced isotope is unstable, and will decay back to the original element: neutrinos are counted by extracting the product and observing these decays.

In radiochemical experiments, the target element (usually chemically bound into a compound such as C2Cl4 or GaCl3, although the SAGE experiment used pure liquid gallium) is exposed for a period comparable to the half-life of the daughter isotope. The daughter isotope is then extracted from the tank (relatively straightforward for the chlorine experiment, where the daughter is an inert gas; rather more of a challenge for the gallium experiments), and the number of radioactive decays counted. It is essential that the extraction is very efficient: typically you are trying to extract a few atoms of the product from tens of tons of the original compound!

As this brief summary of the technique makes clear, radiochemical experiments have absolutely no sensitivity to direction, cannot measure energy (beyond the simple fact that it is greater than the threshold for the reaction) and have very poor time resolution (of the order of weeks). The technique is only used in applications where a low threshold is critical – in practice, solar neutrino experiments.

Examples of radiochemical experiments: Homestake (Ray Davis; chlorine); SAGE (gallium); GALLEX/GNO (gallium).

Liquid scintillator experiments

Liquid scintillators have an impressive pedigree as neutrino detectors, since the neutrino was originally discovered using a liquid-scintillator detector. They are primarily sensitive to electron-antineutrinos, which initiate inverse beta decay of a proton: νe + p → e+ + n. Being organic compounds, liquid scintillators are rich in hydrogen nuclei which act as targets for this reaction. The positron promptly annihilates, producing two gamma rays; the neutron is captured on a nucleus after a short time (a few microseconds to a few hundred microseconds), producing another gamma-ray signal (sometimes the scintillator is loaded with an element such as gadolinium or cadmium, both of which have very high affinities for slow neutrons, to enhance this capture rate). This coincidence of a prompt signal (whose energy gives the antineutrino energy) and a delayed signal (whose energy is characteristic of the nucleus that captures the neutron, e.g. 2.2 MeV for capture on hydrogen) allows the experiment to reject background effectively.

Liquid scintillator detectors have good time and energy resolution, but do not preserve directional information. Although they are usually thought of as electron-antineutrino detectors, they are also sensitive to electron neutrinos via elastic scattering, ν + e → ν + e: the Borexino experiment uses this reaction to study the flux of B-8 solar neutrinos. They have fairly low energy thresholds, typically a few MeV, and are therefore widely used for reactor neutrino experiments.

Examples of liquid scintillator experiments: Borexino (solar neutrino experiment); KamLAND (reactor neutrino oscillation experiment); MiniBooNE (accelerator neutrino oscillation experiment); SNO+ (liquid-scintillator experiment using the SNO hardware, under construction).

Tracking experiments

Tracking detectors reconstruct the path of the charged leptons produced in charged-current interactions, either by the ionisation that they cause or by the energy that they deposit. A magnetic field causes the path of the particle to be bent, allowing the momentum of the charged particle, and the sign of its charge, to be reconstructed. These detectors are best suited to higher energy neutrinos, because the distance that a particle will travel through a detector increases as its energy increases, and longer tracks are easier to reconstruct. For the same reason, they usually perform better with muons (which are penetrating particles that leave well-defined tracks) than with electrons (which produce electromagnetic showers when they travel through dense material). A shower looks different from a muon track, so tracking detectors are usually good at separating muons from electrons; their ability to distinguish electrons from photons depends on the precise nature of the detector (photons also shower in dense material, so detectors made of solid material will have trouble in separating them from electrons; gaseous detectors, in which photons and electrons don’t shower, will see ionisation from electrons but not from photons, and will thus separate them easily).

Compared to other forms of neutrino detector, tracking detectors look much more similar to conventional high-energy physics experiments such as ATLAS or CMS. However, this similarity is a bit misleading. In most particle physics experiments, the interactions take place in a small, well-defined region in the middle of the experiment, which can therefore be designed with a layered structure to take advantage of this: small, high-precision tracking detectors close to the interaction point, larger, lower-precision, less expensive technologies further out. In neutrino experiments, the interaction can happen anywhere in the detector, so any design which involves multiple different technologies must allow for this.

Tracking detectors are good at distinguishing between different event topologies and reconstructing events containing multiple particles (e.g. νμ + p → μ + n + Nπ, where N ≥ 1). These are more likely to occur in higher-energy neutrino beams.

Examples of tracking detectors: MINOS (tracking calorimeter for neutrino oscillations); MINERνA (scintillator tracker for studies of neutrino interactions); ICARUS (liquid argon tracker for neutrino oscillations); T2K ND280 near detector (scintillator tracker and gaseous tracker, for characterisation of T2K beam and studies of neutrino interactions).

Emulsion

The detection of charged-current events from tau neutrinos is particularly challenging, because the tau decays extremely rapidly and is therefore difficult to identify cleanly. The OPERA experiment at the Gran Sasso underground laboratory and the DONUT experiment at Fermilab both addressed this by reviving the long-disused technique of nuclear emulsions.

Nuclear emulsions are simply the sensitive material of photographic film, made into a slab instead of a thin coat, and exposed to the beam. The ionisation produced by the passage of a charged particle causes chemical changes in the emulsion, which become revealed as visible tracks when the emulsion is developed. A fine-grained emulsion can provide micrometre accuracy in track positions: ideal for reconstructing the decay of an extremely short-lived particle.

Emulsions were widely used in the early days of particle physics – indeed, since the discovery of radioactivity occurred due to the fogging of a photographic plate, it could be argued that emulsions were the very first particle detectors. They fell out of fashion because:

  • they are not real-time – you don’t know what you’ve got until you take the emulsion stack out and develop it;
  • they are not inherently digital – scanning the stack and digitising the results is time-consuming and difficult;
  • they can’t be triggered – if a particle goes through your emulsion and leaves a track, the track is there whether the particle was interesting or not;
  • they are one-shot devices – once you take the stack out and develop it, it can’t be reused: if you want to continue taking data, you have to build and install a new stack.

These are cogent disadvantages, and are fatal for high-rate environments such as the LHC. For tau-neutrino experiments, they are not so serious, and the exquisite precision of emulsion tracking was considered worth the trouble: it certainly was for DONUT, which is credited with the discovery – i.e., the first direct observation – of the tau-neutrino.

Water Cherenkov experiments

It is a well-known law of nature that nothing can travel faster than light. However, this really refers to the speed of light in a vacuum. When light travels through a transparent medium such as glass or water, it is slowed to by an amount corresponding to the refractive index of the medium: water has a refractive index of 1.33 so light in water travels at 0.75c. Particles aren’t affected by the refractive index, so a particle travelling at 0.99c in a vacuum will be travelling at faster than the local speed of light if it travels through water.

Diagram of Cherenkov radiation

Figure 7: the geometry of Cherenkov radiation. The particle is travelling left to right at speed βc through a medium with refractive index n. The Cherenkov cone has half-angle θ given by cos θ = 1/nβ. In many cases, the particles can be treated as extremely relativistic, β ∼ 1: in this case the opening angle depends only on the medium, cos θ = 1/n. Figure from Wikimedia Commons

An aircraft travelling faster than the speed of sound emits a sonic boom. Similarly, a particle travelling through a transparent medium at faster than the speed of light in that medium emits a kind of “light boom” – a coherent cone of blue light known as Cherenkov radiation. The particle is travelling down the axis of the cone, so if the cone can be reconstructed the direction of the particle can be measured.

Water Cherenkov detectors for neutrinos can be divided into two types:

Densely instrumented artificial tanks (Super-Kamiokande, SNO)
The water is contained in a tank lined with photomultipler tubes. The Cherenkov light produced by the muon or electron is reconstructed as a ring of hit PMTs. The appearance of the ring can be used to identify the originating particle: muons are single particles, and make sharp rings, whereas electrons (and photons) initiate electromagnetic showers, and the nearly parallel electrons and positrons in the shower combine to make a fuzzy ring. The threshold of these detectors is around 1 MeV or so.
Sparsely instrumented natural water (neutrino telescopes)
A very large volume of natural water is instrumented with a sparse array of photomultipliers dispersed throughout the volume (not concentrated at the edges). The cone geometry is not visually apparent, but can be reconstructed using the time at which each hit photomultiplier records its pulse (the opening angle of the cone is known, because these detectors see only high-energy particles). The threshold of these detectors depends on the spacing of the PMTs, but is normally very high (tens or hundreds of GeV); they reconstruct muons, which make a long straight track, much better than electrons, which deposit all their energy in a fairly small volume and are thus seen by fewer PMTs.

Densely instrumented water Cherenkov detectors were foreseen as neutrino detectors by Fred Reines in 1960, but the pioneering IMB and Kamiokande experiments (made famous by their observations of SN 1987A) were originally conceived as detectors for proton decay. At the time, Grand Unified Theories of particle physics predicted that protons should decay (with an extremely long lifetime, of course) into e+ π0. Since the π0 immediately decays into two gamma rays, this is an ideal decay channel for water Cherenkovs, producing an easily recognisable three-ring signature. The protons failed to cooperate – the proton lifetime for this decay channel now stands at >8.2×1033years – but the experiments proved effective in detecting solar, atmospheric and supernova neutrinos.

Water Cherenkovs can detect the electrons or muons from charged-current interactions, or the recoil electron from neutrino-electron elastic scattering. For solar neutrinos, the latter reaction dominates; for higher-energy neutrinos, the former is more important. Although it might seem that neutrino-electron scattering should be equally sensitive to all types of neutrinos, in fact it is much more sensitive to electron-neutrinos than to other types. This is because electron-neutrinos and electrons can scatter both through neutral-current interactions (the neutrino and electron retain their individual identities, but momentum is transferred from one to the other) and through charged-current interactions (the neutrino converts into an electron, and the electron converts into a neutrino). The presence of this second contribution, which is only possible for electron-neutrinos, greatly increases the chance of interaction. Therefore, water Cherenkovs are essentially electron-neutrino detectors at solar neutrino energies, but detect both electron and muon neutrinos (and flag which is which) at higher energies. (Tau neutrinos are more difficult, for two reasons: because the tau is more massive, the energy threshold above which Cherenkov radiation is emitted is much higher: 0.77 MeV for an electron, 160 MeV for a muon, 2.7 GeV for a tau; also, the tau is extremely short-lived and therefore may not travel far enough to emit much Cherenkov light.) They have good time and energy resolution, and good directional resolution for the detected particle (for low energy neutrinos, this translates into modest angular resolution for the neutrino, because the daughter particle will not be travelling in exactly the same direction as its parent).

Examples of densely instrumented water Cherenkov experiments: Super-Kamiokande (solar neutrinos, atmospheric neutrinos, far detector for K2K and T2K oscillation experiments); IMB (proton decay experiment, 1979–1989, which was one of the two water Cherenkovs to detect neutrinos from SN 1987A).

Examples of neutrino telescopes: IceCube, ANTARES and Baikal.

Heavy-water Cherenkov: SNO

By the mid-1980s, the existence of the solar neutrino problem was becoming established: the theoretical model of the solar interior, the Standard Solar Model of John Bahcall and co-workers, agreed with all observations except the neutrino rate, and all attempts to find a problem with Ray Davis’ experiment had failed. Over the following few years, the deficit of solar neutrinos was confirmed, first by the Kamiokande water Cherenkov experiment and then by the GALLEX and SAGE gallium experiments. It seemed overwhelmingly likely that the source of the problem lay in the behaviour of the neutrino, and specifically in neutrino oscillations. However, there was no “smoking gun”: it could be proven that there was a deficit of electron-neutrinos, but it could not be shown that they had transformed into some other type of neutrino. What was needed was a detector that could directly compare charged and neutral current interaction rates at energies of order 1 MeV, far too low for muon-neutrinos to convert to charged muons.

In 1984, Herb Chen suggested that heavy water might be the solution to the problem. Heavy water, D2O, replaces normal hydrogen by its heavier isotope deuterium (2H or D), whose nucleus contains a neutron in addition to the proton of normal hydrogen. Deuterium is extremely weakly bound, and therefore easily broken up when struck; the key point is that this can happen in two different ways.

  • ν + 2H → p + p + e (charged current), which can only occur for an incoming electron-neutrino;
  • ν + 2H → p + n + ν (neutral current), which can happen for any neutrino.

The binding energy of the deuteron is only 2.2 MeV, so any neutrino with an energy greater than this is theoretically capable of initiating the second of these reactions. The two reactions can be distinguished by detecting the capture of the neutron by an atomic nucleus – D2O is not good at capturing neutrons (which is why it’s used as a moderator, to slow neutrons down in nuclear reactors without reducing the flux), but the heavy water can be loaded with some other substance to improve this (SNO used ordinary salt, NaCl; neutrons capture readily on chlorine-35).

Deuterium is a very rare isotope of hydrogen, so heavy water is expensive and difficult to obtain. Fortunately, the Canadian nuclear power industry uses heavy water in its CANDU nuclear reactors, and the SNO Collaboration was able to borrow 1000 tons from Atomic Energy of Canada Ltd. As the loan was for a fixed time, this did place a hard limit on the lifespan of the SNO experiment, which has now concluded; the vessels used to contain the heavy-water active volume and the light-water outer detector (used to reject through-going muons and other background) are being reused by the SNO+ liquid scintillator experiment.

A heavy-water Cherenkov detector is a nearly perfect experiment for low-energy neutrinos, the only drawback being that the threshold is higher than ideal for solar neutrinos (it can see only B-8 and hep neutrinos). The principal disadvantage is simply the unavailability of kilotons of D2O.