Egos and intensity in the search for dark matter

Voices in the dark.

In the next few weeks, the world’s most sensitive dark matter detector will begin its operations under Italy’s Gran Sasso mountain. This seems a good time to point out that it is sharing the mountain with a detector that may already have found some. What a shame, then, that what might one day be viewed as a historic result has been mired in petty name-calling.

We’ve been looking for dark matter since 1933, when the astronomer Fritz Zwicky pointed out that clusters of galaxies move in ways that seemingly defy the laws of physics. The movement made sense only if the clusters were experiencing a gravitational pull from some invisible stuff nearby.

For various reasons, mostly to do with other astronomers not liking Zwicky very much, we’ve been searching for dark matter seriously only since the 1970s. During those four decades, there has been a series of pronouncements about its discovery being only a decade away. It might now be time to take those pronouncements a little more seriously: lately, the sensitivity of detectors has been improving tenfold every two years. We must surely be on the verge of finally nailing down the existence of dark matter. If we haven’t already, that is.

Dark matter doesn’t just hold gravity clusters together – it’s everywhere. It’s right here on earth, for instance: billions of dark matter particles fly through your body every second. You won’t feel them and they won’t harm you. They don’t interact much with the stuff of our everyday reality, which is what has made them so hard to detect.

While we don’t have any concrete detections of single particles, we do seem to have a discernible signal from passing through clouds of dark matter. It was first spotted by the DAMA dark matter detector, which is based, like the new DarkSide-50 detector, deep under the mountains at Gran Sasso. The rock covering them protects the instruments from distracting sources of noise.

In 2008, DAMA’s operators announced that they had identified a signal that rose and faded with the seasons. It might have been ignored, except that this is exactly what Katherine Freese predicted for a dark matter signal in 1986. She said that the intensity of dark matter detections should depend on the time of year, because as the earth whirls round the sun and the sun moves through the Milky Way, the amount of dark matter hitting the detectors will ebb and flow. It’s rather like the difference between walking into wind-driven rain, then turning and walking the other way. In June, dark matter hits Planet Earth full in the face; in December, it’s at our back.

So, it was pretty exciting that DAMA’s detector saw this predicted pattern. It was even more exciting when another detector, CoGeNT, based in a deep underground mine in Minnesota, also saw it. It’s a shame that a third detector, Xenon, didn’t.

Xenon is also in the Gran Sasso mine and there is no love lost between the leaders of these two research efforts. CoGeNT’s Juan Collar has called Xenon’s science “pure, weapons-grade balonium”. Not content with antagonising his peers, Collar has also accused the DAMA project of “cheapening the level of our discourse to truly imbecilic levels”.

Finding dark matter is proving to be astonishingly difficult and everyone knows there’s a Nobel prize at stake, so it’s not surprising that the claws are out.

Anyway, welcome to the fray, DarkSide-50; there is definitely room for more players in this competition. Whether there is room for more egos, however, is another matter.

Inside the DarkSide-50 experiment.

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 18 February 2013 issue of the New Statesman, Iraq: ten years on

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Tetris and sleep deprivation: how we can help emergency workers cope with trauma

First responders are at serious risk of developing PTSD during events like the Paris attacks. 

Some people seem able to deal with anything. They save a stranger from bleeding out in a bombed restaurant, protect passers-by from heavily armed gunmen, pull dead and dying people out of collapsed buildings, and they keep going because it is their job. These people are first responders.

When trauma goes on for days, as it has recently in Paris, however, the odds of them bouncing back from the violence, death and injury they are witnessing rapidly diminishes. They are at greater risk of developing a severe stress reaction known as post-traumatic stress disorder (PTSD). One study found that the worldwide rate of PTSD among first responders is 10 per cent, much higher than the 3.5 per cent rate among those not involved in rescue work.

Tetris to the rescue

So how best to address the problem? Research is in its infancy, but there are some promising studies. Emily Holmes’ group at the University of Cambridge has been looking at the benefits of playing Tetris, a video game, after a traumatic experience. The idea is that this could block the consolidation of traumatic memories so they don’t “flash back” later on.

For the study, her team first traumatised people by showing them distressing footage from public safety videos. The next day they invited them back into the lab to reactivate the memories with still images taken from the videos. One group then played Tetris for 12 minutes while the other sat quietly. Over the following week, the group who played Tetris had about 50 per cent fewer unwanted memories from the films compared to the group who didn’t.

The team concluded that playing Tetris helped individuals because it soaks up their visual processing capacity, making it harder for the brain to consolidate the visual parts of a traumatic memory.

Since it takes about six hours for the brain to cement a memory, the key is to play the game soon after trauma or within six hours of re-activating the traumatic memory. How long the helpful effects of playing Tetris will last and whether it will translate into helping people after real-life trauma is still unknown.

Talking it through

Other techniques, such as “updating”, taken from a highly-effective talking treatment for PTSD, may be more practical and easier to implement.

Like a detective, updating is a technique that focuses on finding new information and linking it to the case, the past memory. This is necessary because when the brain and body are in survival mode during trauma, the mind finds it difficult to encode all the relevant facts. Often key pieces of information that could make the memory less traumatic are lost. Updating links new information to someone’s memory of their trauma to make it less upsetting.

But can updating help to reduce unwanted memories after trauma?

We carried out a study, published in PLOS ONE, in which we traumatised people by showing them terrifying films of humans and animals in distress. We then divided our participants into three groups. One group watched the films again but were given new information about how long people suffered and whether or not they lived or died – essentially, they were updated. The second group watched the same films again but without the new information. And the third group watched films of humans and animals who were not in distress. The updated group had fewer traumatic memories and PTSD symptoms than the other two groups.

Updating is now being used by some UK emergency services. First responders will gather after critical incidents and update their memories of what happened before they go home.

Sleep deprivation

There are other techniques that may be helpful. One study found that depriving people of sleep may be useful in the aftermath of trauma.

But the same study found that a week after the trauma, people who had been deprived of sleep had the same number of unwanted memories as people who had slept well afterwards. Consequently, it remains unclear whether there would be any long-lasting benefits using this method. There are, however, certainly health risks linked to lack of sleep.

Still looking for a solution

To develop preventative interventions, we need to study newly-recruited emergency workers who haven’t yet suffered on-the-job trauma and follow them over time, spotting which “coping styles”, present before trauma, may predict their reactions afterwards.

For example, some people naturally react to stressful life events by dwelling on them, thinking about why they happened for hours on end. This strategy, called rumination, has been linked to PTSD in people who survived car crashes.

If rumination predicts PTSD in first responders, then preventative interventions could train people to spot when they are dwelling on an event and refocus their attention to the task at hand.

When we have identified which factors heighten emergency workers’ risk of developing PTSD, programmes can be developed to target those vulnerabilities. Only then can an intervention, directed at first responders most at risk of developing PTSD, properly protect them in their line of work.

The Conversation

Jennifer Wild is a Senior Research Fellow in Clinical Psychology at the University of Oxford

This article was originally published on The Conversation. Read the original article.