Antarctica is one of the most extreme places on the earth, keeping this southern continent free from permanent human inhabitation. Though still a largely unexplored area, activity bubbles on the icy terrain, with "extreme science" being performed in numerous disciplines.
One such extreme experiment is the IceCube Neutrino Observatory project, headed by University of Wisconsin-Madison (UW-Madison). The $274 million project is geared toward the detection of neutrinos–subatomic particles that are a result of radioactive decay. Neutrinos are good candidates for intergalactic research because they lack an electric charge; are incredibly small, allowing them to pass through dense matter; stay in a straight trajectory; and travel at the speed of light.
Massive equipment is required to detect neutrinos. Scientists involved with the IceCube project are using specialized sensors called Digital Optical Modules (DOMs) to create one of the world's largest neutrino telescopes. Data from the telescope will be used by the Antarctic Astronomy and Astrophysics Research Institute to understand supernova explosions, gamma-ray bursts, black holes and other intergalactic events. Correlating the number and energy of the detected neutrinos with these events will help to explain their nature, as well as to help us understand the sources of dark energy and dark matter.
It is essential for each module to be in good working order and to stay connected to the main network of sensors. To make sure the sensors operate at top performance, Rabbit's RabbitCore® RCM4200 is used for extreme monitoring connectivity.
Timothy Murray, a lead programmer and project manager for the DOM Connectivity Monitoring (DCM) system, understands the importance of equipment reliability for a project of this magnitude. The complete installation will employ about 4,800 DOMs. It is imperative that each of these modules is in excellent working condition and is connected to the main cable line. Once deployed, the modules will be frozen into place, becoming irretrievable and un-maintainable. To ensure that each DOM is in working order, Murray uses the RCM4200 in the DCM.
The DCM is comprised of a custom PC containing digital switches that connect to the 60 DOMs on any given main cable. The RCM4200 sits atop the custom PC board, controlling the switches and the SPI A/D converter. Every five seconds, the RCM4200 refreshes a webpage displaying the status of all 60 DOMs via an Ethernet connection to a PC in the main station. During the installation phase as each DOM is connected to main cable, the system emits an audible sound and produces a visual display on a webpage at 4-second intervals. The DCM custom PC board and RCM4200 are mounted on the reel spool holding the main cable.
During the installation process, a hot water drill melts away a hole into the ice that will become 2450 meters deep. Over an 8-hour span, 60 DOMs are lowered into the hole. As the DOMs are lowered, the RCM4200 polls all 60 DOMs to make sure they are working and are securely connected to the main cable. Since the system refreshes every 5 seconds, the status of the DOMs is maintained on a near real-time basis. If a DOM malfunctions or becomes disconnected, the RCM4200 will detect the particular DOM and display it on a webpage. Since the instillation process is slow, researchers are able to fix the problem before the problematic DOM is lowered into the ice.
"The DCM's role of making sure the DOMs are connected properly is very important," says Murray, also noting that the RCM4200 plays an essential role in the process. "Rabbit gave us the ability to do this. Without the RCM4200, we would really have no other way to install the DOMs reliably."
The cost of this project requires smooth operation and reliability. Along with the sensitive nature of the project in terms of research and installation, equipment failure must be avoided. The features and software give Murray and team the edge they need to produce a 99 percent assurance rate that each DOM is in working order.
"The programming of the RabbitCore had to be as streamlined as possible. I was amazed by the RabbitCore's ability to accurately control the circuit down to the millisecond. The RabbitWeb and Dynamic C® software packages made it easy for me to generate a webpage with live data," Murray states.
The RCM4200 offers robust features that make it perfect for this project.
"Once I researched Rabbit products, I was also amazed by the processing power of all the boards. The analog and digital I/O of the boards was outstanding, but of course the price was a huge factor. Another factor that also played a major role was the RCM4200's ability to operate in -25 degree temperatures," says Murray.
Timothy Murray and the UW-Madison project team found a cost-effective, easy-to-design and reliable solution that accurately monitors the Digital Optical Modules. With Rabbit's RCM4200 RabbitCore module, the IceCube Neutrino Observatory is making strides in extreme science.
For more information on the IceCube project, visit: icecube.wisc.edu