page_title: Antiproton Decelerator
section_title: GBAR
hierarchical_section_title: Antiproton Decelerator / GBAR
caption_attribution_description: Français&#160;: Expérience GBAR
context_page_description: The Antiproton Decelerator is a storage ring at the CERN laboratory near Geneva. It was built as a successor to the Low Energy Antiproton Ring and started operation in the year 2000. Antiprotons are created by impinging a proton beam from the Proton Synchrotron on a metal target. The AD decelerates the resultant antiprotons to an energy of 5.3 MeV, which are then ejected to one of several connected experiments.
context_section_description: GBAR (Gravitational Behaviour of Anti hydrogen at Rest), is a multinational collaboration at the Antiproton Decelerator (AD) of CERN.
  The GBAR project, aims to measure the free fall acceleration of ultracold neutral anti hydrogen atoms in the terrestrial gravitational field. The experiment consists preparing anti hydrogen ions (one antiproton and two positrons) and sympathetically cooling them with Be ⁺ ions to less than 10 μK. The ultracold ions will then be photoionized just above threshold, and the free fall time over a known distance measured.
caption: CERN Antimatter factory – GBAR (Gravitational Behaviour of Anti hydrogen at Rest) experiment
exif: {"Image ImageDescription": "", "Image Make": "SONY", "Image Model": "NEX-6", "Image Orientation": "Horizontal (normal)", "Image XResolution": "350", "Image YResolution": "350", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "NEX-6 v1.00", "Image DateTime": "2019:08:19 11:00:19", "Image WhitePoint": "[313/1000, 329/1000]", "Image PrimaryChromaticities": "[16/25, 33/100, 21/100, 71/100, 3/20, 3/50]", "Image YCbCrCoefficients": "[299/1000, 587/1000, 57/500]", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "480", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 51, 48, 48, 0, 0, 3, 0, 2, 0, 1, 0, ... ]", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail ImageDescription": "", "Thumbnail Make": "SONY", "Thumbnail Model": "NEX-6", "Thumbnail Orientation": "Horizontal (normal)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail Software": "NEX-6 v1.00", "Thumbnail DateTime": "2019:08:19 11:00:19", "Thumbnail JPEGInterchangeFormat": "37152", "Thumbnail JPEGInterchangeFormatLength": "10585", "Thumbnail YCbCrPositioning": "Co-sited", "EXIF ExposureTime": "1/60", "EXIF FNumber": "4", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "400", "EXIF SensitivityType": "Recommended Exposure Index", "EXIF RecommendedExposureIndex": "400", "EXIF ExifVersion": "0230", "EXIF DateTimeOriginal": "2019:08:19 11:00:19", "EXIF DateTimeDigitized": "2019:08:19 11:00:19", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF BrightnessValue": "3417/1280", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "463/128", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "16", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "4912", "EXIF ExifImageLength": "3264", "Interoperability InteroperabilityIndex": "R03", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "36868", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF FocalLengthIn35mmFilm": "24", "EXIF SceneCaptureType": "Standard", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF LensSpecification": "[16, 50, 7/2, 28/5]", "EXIF LensModel": "E PZ 16-50mm F3.5-5.6 OSS", "EXIF Gamma": "11/5"}