Introduction Science Experiment 2012 pGAPS Flight Papers & Talks GAPS Team Internal

Recent News

  • January 2017: GAPS approved for funding in U.S. NASA has approved the 2016 GAPS proposal. The GAPS team can now move forward to finalize the design of the instrument and proceed towards its construction. A first science flight of GAPS on a long-duration balloon in the Antarctic would be in Fall 2020.
  • June 2014: First Anti-deuteron workshop held. The first workshop dedicated to astrophysical anti-deuterons was held at UCLA. The two-day meeting, organized by Philip von Doetinchem and Rene Ong, brought together world-experts in the area of anti-deutereons that resulted in a review article published in Physics Reports.

A rendering of the detector design.

Introduction

An Indirect Dark Matter Detector

GAPS (General Antiparticle Spectrometer) is an experiment under development to search for the anti-deuteron particle in the cosmiic rays. Astrophysically produced anti-deuterons have never been detected and so the unambiguous detection of even a single event would be very significant. Anti-deuterons could also be a tell-tale signature of dark matter annihilations.

GAPS, initially configured as a long-duration balloon experiment, will detect anti-deuterons with an effectively background-free method. Anti-deuterons produced by the annihilation of weakly interacting massive particles (WIMPs), a well-motivated dark matter candidate, will be captured in the GAPS target material, resulting in an exotic atom in an excited state. This exotic atom will then quickly decay, producing X-rays of precisely defined energies and a correlated pion signature from nuclear annihilation.

The method of detection uses a time-of-flight (TOF) system, which tags candidate events and particle velocities and planes of pixillated Si(Li) detectors, which serve as the target material and tracking detector. The Si(Li) detectors provide both excellent X-ray energy resolution and good particle tracking. The GAPS exotic atom detection method has already been successfully tested in an accelerator environment at KEK in 2004 and 2005. To test the hardware appropriate for GAPS, a balloon-borne prototype experiment with a TOF system and 6 Si(Li) detectors was successfully flown in June 2012 from the Taiki balloon base of the Japanese space agency JAXA.

At low energies, anti-deuteron is rarely
produced by cosmic rays while dark
matter models present a high flux,
resulting in an effectively background
free experiment.

Science

WIMP Self-annihilation

Approximately 90% of the mass in the universe is dark matter and discovering its nature is one of the most pressing goals in science. It is hypothesized to be a new particle which is both cold and non relativistic, a WIMP (weakly interacting massive particle). A leading WIMP dark matter candidate is the hypothetical neutralino. The neutralino is predicted by supersymmetric (SUSY) extensions to the standard model and is a heavy, stable particle with the WIMP properties.

In contrast to direct searches and accelerator experiments, GAPS will look for WIMPs their their self-annihilation signal into anti-deuterons, thus providing a complementary search technique. Anti-deuterons from WIMP annihilations should be produced in areas with high dark matter density and hence a high annihilation rate. In addition, GAPS will also explore other anti-deuteron sources, such as evaporating primordial black holes.

Anti-deuteron detection is a novel approach to the dark matter hunt. While anti-protons are more copiously produced in WIMP annihilation, they are difficult to distinguish from anti-protons produced in ordinary cosmic ray interactions. Cosmic rays, however, rarely produce anti-deuterons below 1 GeV. Furthermore, dark matter models predict a relatively high anti-deuteron flux in this energy range. Thus, at low energies, anti-deuteron detection is effectively a background free signture of dark matter.

Experiment

Previous Experiments

A GAPS prototype was tested at the KEK accelerator in 2004 and 2005. When anti-protons were dumped into the target, X-ray events with multiple signatures were detected. Furthermore, pion stars provided additional anti-particle identification and non anti-particle background was clearly identified and rejected. These experiments successfully demonstrated the multi X-ray and pion detection method to identify anti-particles. Furthermore, the absolute X-ray transition yields for anti-protons were measured for the first time in several target material.

The prototype instrument

Based on the accelerator testing and extensive design studies, we have designed a flight instrument capable of reaching deep into the parameter space of many cold dark matter models. The heart of the instrument consists of layers of coarsely pixilated Si(Li) detectors that function as both a target in which exotic atoms are formed and a detector of the subsequent atomic transition X-rays. The Si(Li) detectors also serve as a particle tracker for the incoming anti-particle as well as the annihilation pions. An array of plastic scintillators surrounding the Si(Li) detectors serves as a time of flight (TOF) trigger, providing a measurement of the incoming anti-particle velocity.

Si(Li) detectors

Detection

GAPS provides a nearly background free technique of identifying anti-deuterons by using three different methods of detection for every event. Initially, a plastic time of flight (TOF) system tags the particle and records the velocity. This will distinguish anti-deuterons from lighter particles, such as anti-protons. The particle then slows down and stops in the target, forming an excited exotic atom. This atom then de-excites and releases both X-rays and a pion star.

Si(Li) wafers will be hexagonally packed into ten layers as the detectors. These have a timing of 50 ns and a 2 keV energy resolution while requiring a two X-ray coincidence for detection. Because the X-ray energy only depends on the mass and charge of the particle, X-ray energy signatures precisely determine the type of antiparticle detected as it makes transitions to lower states. The pion star, the third layer of detection, provides greater background suppression.

2012 pGAPS Flight

Prototype GAPS (pGAPS) Flight

The pGAPS payload was built to test all the components and techniques necessary for a full size GAPS experiment including Si(Li) detectors with a radiator-based cooling system, a scintillator-based TOF system, and readout and control electronics.

The science component of the payload consisted of three layers of crossed scintillator paddles (16 paddles total) with PMT readout on both ends of each paddle (32 total PMT readouts) as well as six 10cm Si(Li) detectors with active cooling (down to ~40C operationg temperature).

Other ballon-craft components of the payload such as the balloon, rotator ballast, GPS, gyro, datalink , and the battery power were provided by JAXA.

Before Launch
The science payload
Launch
Balloon Filling
Before Launch
Preparing the payload for launch
Launch
Payload on launcher

On June 3rd, 2012, the pGAPS experiment was successfully flown on a high-altitude scientific balloon. The flight took place from the Taiki Aerospace Research Field operated by JAXA and located on the east coast of Hokkaido Prefecture, Japan.

Before Launch
Ready for launch
Launch
Balloon released

The total flight was over 6 hours long, with more than 3 hours (the maximum expected) of operation of float altitude (~33km). Over one million cosmic ray triggers were recorded, and the instrument was operated in several trigger modes to allow for a through testing of all different detector systems. Both the time-of-flight system and Si(Li) systems performed well in-flight with no PMT failures or any evidence of high-voltage corona discharge.

After cut-down, the payload was recovered within several minutes of touch down in the ocean and was brought back to the balloon facility for cleaning and packing for shipment back to the US. The flight data copied from the gongola within 1 hour of the payload returning to the base.

Launch
Retrieving the payload
Before Launch
Recovered Payload

The goals for this flight were to measure the cosmic-ray and X-ray background and rate, test our thermal model, and demonstrate the operation of Si(Li) detectors in a high-altitude environment. More analysis of the data still remains, but we are confident that all of our goals have been met.

Launch
2012 pGAPS Flight Team

Click here for more pictures and video of the flight!

Papers and Talks

The GAPS Experiment to Search for Dark Matter using Low-energy Antimatter - arXiv
R.A. Ong et al., Proc. 35th Int. Cosmic Ray Conf. (ICRC 2017), Busan, Korea, July 2017; Talk (pdf).

Antideuteron Sensitivity for the GAPS Experiment - arXiv
T. Aramaki, C.J. Hailey, S.E. Boggs, P. von Doetinchem, H. Fuke, S.I. Mognet, R.A. Ong, K. Perez, J. Zweerink, Astroparticle Physics 74, 6 (2016).

Review of the theoretical and experimental status of dark matter identification with cosmic-ray antideuterons - arXiv
T. Aramaki, S. Boggs, S. Bufalino, L. Dal, P. von Doetinchem, F. Donato, N. Fornengo, H. Fuke, M. Grefe, C. Hailey, B. Hamilton, A. Ibarra, J. Mitchell, I. Mognet, R. A. Ong, R. Pereira, K. Perez, A. Putze, A. Raklev, P. Salati, M. Sasaki, G. Tarle, A. Urbano, A. Vittino, S. Wild, W. Xue, K. Yoshimura, Physics Reports 618, 1 (2016).

GAPS: General AntiParticle Spectrometer - PDF
P. von Doetinchem, TeVPA 2016 (CERN).

GAPS - Dark Matter Search with Low-energy Cosmic-ray Antideuterons and Antiprotons - arXiv
P. von Doetinchem, T. Aramaki, S. Boggs, H. Fuke, C.J. Hailey, S.I. Mognet, R.A. Ong, K. Perez, J. Zweerink, Int. Cosmic Ray Conf. 2015 (The Hague).

Status of Cosmic Anti-Deuteron Searches - arXiv
P. von Doetinchem, T. Aramaki, S. Boggs, S. Bufalino, L. Dal, F. Donato, N. Fornengo, H. Fuke, M. Grefe, C. Hailey, B. Hamilton, A. Ibarra, J. Mitchell, I. Mognet, R.A. Ong, R. Pereira, K. Perez, A. Putze, A. Raklev, P. Salati, M. Sasaki, G. Tarle, A. Urbano, A. Vittino, S. Wild, W. Xue, K. Yoshimura, Int. Cosmic Ray Conf. 2015 (The Hague).

Poster: General AntiParticle Spectrometer (GAPS) Dark Matter Search with Low-energy Cosmic-ray Antideuterons and Antiprotons - PDF
P. von Doetinchem, Int. Cosmic Ray Conf. 2015 (The Hague).

Potential for Precision Measurement of Low-Energy Antiprotons with GAPS for Dark Matter and Primordial Black Hole Physics - arXiv
T. Aramaki, S. E. Boggs, P. von Doetinchem, H. Fuke, C. J. Hailey, S. A. I. Mognet, R. A. Ong, K. M. Perez, J. Zweerink, Astroparticle Physics 59, 12 (2014).

GAPS Antiproton and Antideuteron Measurement for Indirect Dark Matter Search - PDF
T. Aramaki, C. Hailey, UCLA Dark Matter 2014 (February 2014).

The Flight of the GAPS Prototype Experiment - arXiv
P. von Doetinchem, T. Aramaki, N. Bando, S. E. Boggs, H. Fuke, F. H. Gahbauer, C. J. Hailey, J. E. Koglin, S. A. I. Mognet, N. Madden, S. Okazaki, R. A. Ong, K. M. Perez, T. Yoshida, J. Zweerink, Astroparticle Physics 54, 93 (2014).

The GAPS Experiment: Hunting for Dark Matter with Antideuterons - PDF
Kerstin Perez, Int. Cosmic Ray Conf. 2013 (Rio de Janeiro).

GAPS: A Dedicated Search for Anti-Deuterons in the Cosmic Rays - PDF
Rene A. Ong, Snowmass 2013, Cosmic Frontiers 6 Subgroup, SLAC Workshop (March 2013).

The General AntiParticle Spectrometer - PDF
Philip von Doetinchem, Snowmass 2013, Cosmic Frontiers 6 Subgroup, SLAC Workshop (March 2013).

The Prototype GAPS (pGAPS) Experiment - arXiv
S. A. I. Mognet, T. Aramaki, N. Bando, S. E. Boggs, P. von Doetinchem, H. Fuke, F. H. Gahbauer, C. J. Hailey, J. E. Koglin, N. Madden, K. Mori, S. Okazaki, R. A. Ong, K. M. Perez, G. Tajiri, T. Yoshida, J. Zweerink, Nuclear Instruments and Methods in Physics Research A 735, 24 (2014).

The pGAPS experiment: an engineering balloon flight of prototype GAPS - arXiv
Hideyuki Fuke, Rene A Ong, Tsuguo Aramaki, Nobutaka Bando, Steven E Boggs, Philip v Doetinchem, Florian H Gahbauer, Charles J Hailey, Jason E Koglin, Norm Madden, Samuel Adam I Mognet, Kaya Mori, Shun Okazaki, Kerstin M Perez, Tetsuya Yoshida, Jeffrey Zweerink (March 2013) .

Development of a meter-scale U-shaped Oscillating Heat Pipe for GAPS - PDF
Shun Okazaki, Hideyuki Fuke, Hiroyuki Ogawa, Takuma Okubo, Yoshiro Miyazaki (July 2012).

UCLA Dark Matter Conference:Search of Antideuteron With GAPS - PDF
P. von Doetinchem (February 2012).

Poster: Dark Matter Search Using Cosmic-Ray Anitdeuterons - PDF
P. von Doetinchem (April 2011).

Poster from INPAC 2011 - PDF
S. A. I. Mognet (2011).

APS Talk - PDF
S. A. I. Mognet (2011).

UC Berkely pGAPS Presentation - PDF
P. Von Doetinchem (October 2010).

Development of the General Antiparticle Spectrometer - PDF
R.A. Ong, AAS 2009 Meeting (Long Beach) (2009).

Antideuterons as an Indirect Dark Matter Signature: Si(Li) Detector Development and a GAPS Balloon Mission (Paper) - PDF
T. Aramaki et al. (November 2008) .

Antideuterons as an Indirect Dark Matter Signature: Si(Li) Detector Development and a GAPS Balloon Mission - PDF
T. Aramaki (November 2008).

Development of large format Si(Li) detectors for the GAPS dark matter experiment - PDF
T. Aramaki et al. (August 2008) .

Antideuterons as an Indirect Dark Matter Signature: Design and Preparation for a Balloon-born GAPS Experiment - PowerPoint
Oral presentation, The Hunt for Dark Matter: a Symposium on Collider, Direct and Indirect Searches (May 2007).

Current status and future plans for the general antiparticle spectrometer (GAPS) - PDF
Fuke, H.; Koglin, J. E.; Yoshida, T.; Aramaki, T.; Craig, W. W.; Fabris, L.; Gahbauer, F.; Hailey, C. J.; Jou, F. J.; Madden, N.; Mori, K.; Yu, H. T.; Ziock, K. P. (February 2007).

Antideuterons as an Indirect Dark Matter Signature: Design and Preparation for a Balloon-born GAPS Experiment - PowerPoint
J.E. Koglin et al., submitted for publication in the Journal of Physics: Conference Series, the proceedings for the 10th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2007).

Antideuterons as an Indirect Dark Matter Signature: Design and Preparation for a Balloon-born GAPS Experiment - PDF
J.E. Koglin, T. Aramaki, S. E. Boggs, W.W. Craig, H. Fuke, F. Gahbauer, C.J. Hailey, N. Madden, K. Mori, R.A. Ong, T. Yoshida, H. T. Yu, and K.P. Ziock, submitted for publication in the proceedings for the 30th International Cosmic Ray Conference (2007).

Indirect Dark Matter Search with Antideuterons: Progress and Future Prospects of GAPS - PDF
J.E. Koglin el al., Nuclear Physics B (Proceedings Supplements for the 7th UCLA Symposium: Sources and Detection of Dark Matter and Dark Energy in the Universe) (2007).

Accelerator testing of the general antiparticle spectrometer; a novel approach to indirect dark matter detection - PDF
Hailey, C. J.; Aramaki, T.; Craig, W. W.; Fabris, L.; Gahbauer, F.; Koglin, J. E.; Madden, N.; Mori, K.; Yu, H. T.; Ziock, K. P. (January 2006).

Indirect Dark Matter Search with Antideuterons: Progress and Future Prospects of GAPS - PowerPoint
Oral presentation, New Views on the Universe, Kavli Institute Inaugural Symposium in Honor of David Schramm (December 2005).

GAPS Team

The following scientists comprise the GAPS team (as of March 2017):

Columbia University
C.J. Hailey, F. Gahbauer, N. Saffold

Massachusetts Institute of Technology
R. Carr, K. Perez, F. Rogers

University of California, Berkeley
S.E. Boggs

University of California, Los Angeles
R. Bird, R.A. Ong, J. Zweerink

University of Hawaii at Manoa
P. von Doetinchem, C. Gerrity

Penn State University
S.I. Mognet

Lawrence Livermore National Laboratory 
W.W. Craig

Oak Ridge National Laboratory
L. Fabris

Institute of Space & Astronautical Science, Japan Aerospace Exploration Agency
H. Fuke

INFN-Trieste
M. Boezio