LBNL Group History

IceCube Acronym Dictionary

A brief history of LBNL's involvement in High-Energy neutrino astronomy with AMANDA and IceCube

Milestones:

1994    Interest in high-energy neutrino astronomy develops at LBNL around community efforts to build a cubic-kilometer-sized detector.

1996   Submission of a multi-institution Letter of Intent to the US DOE for support of R&D for km3 technology.  The LOI emphasizes the Digital Optical Module technology, developed at LBNL.

1997   Two DOMs built by JPL and LBNL are deployed by AMANDA at the South Pole and reveal complex waveforms

1997    After evaluating prospects for detectors in the ocean and at the South Pole, LBNL joins AMANDA with a long-term view to IceCube.

1998    LBNL convinces AMANDA to deploy forty DOM's for evaluation.  LBNL collaborates with DESY and U. Wisconsin to design and build these modules.

1999     The AMANDA Collaboration submits proposal for IceCube, a cubic kilometer detector, to the NSF.

2000    String 18 (the digital string) is deployed by AMANDA

2001     Nanosecond timing demonstrated with String 18. IceCube review committee selects DOM technology for IceCube.

2001     IceCube review committee selects DOM technology for IceCube.

2002    First funds arrive for IceCube.  LBNL scope of work expands.

2004    Printed circuit boards delivered for assembly into DOMs and deployment.  Work on DAQ Software and Experiment Control at LBNL expands.

2005     IceCube deploys the first IceCube string and IceTop tanks.  DOMs work as specified, or better.

2006     IceCube deploys eight more strings.

2007    IceCube deploys 13 more strings. First IceCube paper, on atmosphoeric neutrino flux. The paper is available here.

Narrative:

Neutrino physics at LBNL began with early investigations into double beta decay using intrinsic germanium detectors and reappeared briefly in the 1980's with the ill-fated activity around the "17 keV neutrino."  LBNL's participation in the Sudbury Neutrino Observatory, which began in 1989, marks the start of the current period of major effort in the neutrino sector.   For a while SNO was the only neutrino experiment at LBNL, but in the mid 1990's additional new directions were initiated.  One of these was in high-energy neutrino astrophysics, which has evolved into the present LBNL participation in IceCube.  This is a brief description of how our LBNL IceCube group evolved to its present state (2006).

In the spring of 1994 several of us attended workshops on high-energy neutrino detectors at the Jet Propulsion Laboratory in Pasadena and on high-energy cosmic-ray detectors at FermiLab.  Comparing notes on the opportunities in these areas, we concluded that the neutrino area was where we could hope to make some fundamental technical contributions and influence the directions the field could take.  Meanwhile, the Nuclear Science and Physics Divisions at the Lab formed an Institute for Nuclear and Particle Astrophysics and high-energy neutrino astronomy seemed like an ideal area for this Institute to foster.

During the next two years a series of workshops and discussions resulted in the submission of a Letter of Intent entitled "Technology Development for a Neutrino Astrophysical Observatory" to the U.S. Department of Energy (LBL-38321, UC-412; February, 1996).  This document laid out a plan for developing, deploying and testing an active optical module (photomultiplier tube and associated electronics inside a pressure-resisting glass sphere) based on analog-to-digital conversion in the module, and digital transmission of the data to the surface.  UC Berkeley and the Space Sciences Laboratory, the Jet Propulsion Laboratory, the Universities of Washington, Hawaii, Arizona, and UC Riverside as well as LBNL joined in this Letter of Intent.  Tests and deployments in the ocean and in Antarctic Ice were envisioned, as this technology was considered appropriate for both media. 

This LOI did not result in any funding from the US DOE (indeed, the DOE terminated the support of the DUMAND detector not long afterward) but many of the technical advances described in this report have become embodied in the current designs for Nestor and ANTARES (both deployed in the Mediterranean Sea) and in AMANDA and IceCube, in Antarctica.  The first few Digital Optical Modules were built at JPL and deployed by AMANDA in 1997.  They delivered PMT waveforms to the surface electronics, with many of these waveforms showing interesting complexity arising from multiple photon detection.

Although AMANDA was still experimenting with different data acquisition and transmission technologies, their ability to drill holes in the ice and deploy strings of modules was well established.  Plans for a much larger detector were being discussed.  The existing strings (AMANDA B-10) were showing that the scattering of light in the ice was a tractable problem and muon tracks could be reconstructed with sufficient accuracy to do neutrino astronomy.  Most of us at LBNL decided to cast our lot with ice instead of water and in 1997 joined the AMANDA collaborations with a view toward IceCube in the future.  Two years later, in November 1999, the IceCube Collaboration submitted its proposal for a Kilometer-Scale Neutrino Observatory to the National Science Foundation.

String 18 incorporated dual technologies, i.e., the DOMs also used fiber optic transmission of analog PMT signals so that String 18 would provide the same kind of data as the other strings deployed that season.  The AMANDA array could then function for routine data collection independent of the performance of the digital technology.

The deployment was successful.  All 40 DOMs communicated with the surface just after deployment.  With the high voltage on, waveforms were generated and transmitted to the surface.  It was not until the following season, however, that the timing could be demonstrated.  With the installation of surface DAQ readout cards incorporating master clock signals in 2001, an overall timing resolution of 5 ns was demonstrated.

In the meantime, detailed planning for IceCube was proceeding and it became necessary to decide which technology (fiber optic, digital, or some combination of the two) should be chosen for IceCube.  A technical review committee was formed and, in 2001, the decision was made to pursue the DOM technology for IceCube.

During the period between the deployment of String 18 and the arrival of funding for IceCube, a combination of NSF funds through university R&D grants and Laboratory Directed R&D funds enabled a small group alive to pursue the evaluation of String 18 and do design development for IceCube.   This lean period eventually ended when IceCube became a line item in the NSF's Major Research Equipment and Facilities budget, and project construction funds began to flow to LBNL, through the University of Wisconsin, the lead institution for IceCube.  While these lean years delayed the full exploitation of String 18 capability, by January 2004 sufficient data was accumulated and analyzed to result in the 2005 publication of a paper on the DOM technology in Nuclear Instruments and Methods.   In the meantime, LBNL was designing and testing the electronics for the IceCube DOMs.  Their performance was demonstrated at about the same time that R&D activities were concluded on String 18.

The responsibilities that LBNL assumed for DAQ Hardware and DAQ Software required a rapid build-up of the size of our group.  The white-knuckle approach of 1999-2000 in which modules were designed, tested and deployed all within a year was to be replaced by a more methodical approach with much more testing and design review/revision and attention to reliability.  Project management, documentation, design interfaces, etc. assumed greater importance.   Soon, over 25 FTE at LBNL were working on IceCube. 

The first IceCube deployments were scheduled for January 2005 and would require 256 DOMs plus spares. LBNL's principal hardware deliverable is the main printed circuit board in the DOM and the surface readout electronics (DOM HUBs).  The software for the DAQ is an LBNL responsibility and involves collaboration-wide participation.  Through a large, collaboration wide-effort this all came together in time for the 2005 season and the first IceCube string was deployed.  It worked to specification, and better.

Subsequently, larger numbers of DOM mainboards and HUBs have been produced, tested, and delivered to other institutions in the collaboration for eventual deployment in the 2005-2006 season. By the end of this season eight more strings will have been deployed (along with the associated IceTop surface tanks) and IceCube will have a total of 540 DOMs in the deep ice - almost as many as in AMANDA.  In addition to meeting the deliverables for DAQ Hardware and Software, and for Experiment Control, the LBNL group is involved in other aspects of IceCube that will lead to the operation of IceCube for data analysis - simulations, monitoring, verification, and run operations.  A key step remaining for the LBNL IceCube group will be to secure funding for physics analysis.  Physics analysis is beginning.

With completion of IceCube scheduled for 2010, a lot of history remains to be written.

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