# Presentation: 310971

## The BESS-Polar II Long Duration Flight above Antarctica

- *) CRESST/USRA

- Makoto Sasaki 1,*) for
- The BESS-Polar Collaboration

**1) T. Hams, J. W. Mitchell, R. E. Streitmatter**
**2) S. Haino, M. Hasegawa, A. Horikoshi, Y. Makida, S. Matsuda,**
**      ****M. Nozaki, J. Suzuki, K. Tanaka, A. Yamamoto, K. Yoshimura**
**3) H. Fuke, T. Yoshida**
**4) K. C. Kim, M. H. Lee, E. S. Seo**
**5) A. Kusumoto, Y. Matsukawa, R. Orito**
**6) J. Nishimura, K. Sakai, R. Shinoda**
**7) J. F. Ormes, N. Thakur**

**NASA / Goddard Space Flight Center**
**High Energy Accelerator Research**
**                                        ****Organization**
**ISAS / JAXA**
**University of Maryland**
**Kobe University**
**The University of Tokyo**
**University of Denver**

- The 37th COSPAR SCIENTIFIC ASSEMBLY
- July 17th, 2008

## Contents

_**Contents**_

-  Introduction
-  BESS-Polar II
-  Preparation
-  Flight
-  Status
-  Summary

## Contents

_**Contents**_

-  Introduction
-  BESS-Polar II
-  Preparation
-  Flight
-  Status
-  Summary

## BESS Experiment

_**BESS Experiment**_

**1) Introduction**

- Science ObjectiveStudy elementary particle phenomena in early Universe
- Matter/Antimatter asymmetry
- Primordial black-hole, SUSY darkmatter

- Balloon-borne Experiment with a Superconducting Spectrometer

- BESS-Polar Experiment ( for very precise measurement of low energy antiprotons )
-  Higher Statistics
-  Long duration flight
- Use Solar-Panel ( M. Hasegawa, July 18 10:00 ~ [PSB1-0065-08])
- New DAQ system for Low Power Consumption (R. Orito [PSB1-0017-08 ])
-  Lower energy particles
-  Higher latitude
- Flight above Antarctica ( Polar flight )
-  Solar minimum
-  Ultimate small material
- Thin Solenoid Coil, New Detector (Middle TOF)

-  Most antiprotons are secondary.
-  Enhance flux at low energy?

## BESS-Polar 1st Flight

_**BESS-Polar 1**__**st**__** Flight**_

**1) Introduction**

- BESS-Polar I Flight Summary
-  Launch date: Dec. 13, 2004
-  Flight time: 8 days and 13 hours
-  Cosmic-ray observed: 900 M events
-  Data size: 2.1 TBytes
-  Flight altitude: 37 ~ 39 km (5~4 g/cm2)

- Floating

- Altitude ~38000mResidual air ~4g/cm2

**Launch**

**Landing**

- BESS-Polar I flight was successful
- except
-  TOF PMT HV leak
- 18/44 PMT were inoperative during the flight
-  ACC rejection was not sufficient
-  pbar can be identified up to 1.28 GeV

- Prepared for the BESS-Polar II ( Longer flight time, Fix the problems,  Improve the detectors ...)

## Contents

_**Contents**_

-  Introduction
-  BESS-Polar II
-  Preparation
-  Flight
-  Status
-  Summary

## Contents

_**Contents**_

-  Introduction
-  BESS-Polar II
-  Preparation
-  Flight
-  Status
-  Summary

## BESS-Polar IIDetector

_**BESS-Polar II**__**Detector**_

**2- (a) Preparation**

- Longer Flight Time
- Increase the Magnet Cryogen Life
- Enlarge the Data Storage Size
- Fix the Problems
- Pressurized Enclosure for the TOF PMT
- Improve the Performance
- Improve the Rejection Power for the Aerogel Cherenkov Counter
- Both side read out for the Middle TOF

## Longer Flight Time

_**Longer Flight Time**_

**2- (a) Preparation**

- Increase the Magnet Cryogen Life
- Larger liquid He reservoir tank
- Improved thermal insulation
- Cryogen Life 11 days -> 22.5 days
- Enlarge the Data Storage Size
- Larger Capacity of Hard Disk Drive
- Increase the total number of HDD’s
- 3.6 TBytes -> 16 TBytes

## Longer Flight Time

_**Longer Flight Time**_

**2- (a) Preparation**

- Increase the Magnet Cryogen Life
- Larger liquid He reservoir tank
- Improved thermal insulation
- Cryogen Life 11 days -> 22.5 days
- Enlarge the Data Storage Size
- Larger Capacity of Hard Disk Drive
- Increase the total number of HDD’s
- 3.6 TBytes -> 16 TBytes

## Fix the Problem

_**Fix the Problem**_

**2- (a) Preparation**

**Number of PMTs**

**Days from launch**

- BESS-Polar I

- BESS-Polar I
- TOF PMT HV Leak Problem

- For the BESS-Polar II
- Pressurized Enclosure for the PMT
- Details in [E19-0031-08]

- Resin potting was used for PMTs

- 18/44 PMT were inoperative during the flight

## Improve the Performance

_**Improve the Performance**_

**2- (a) Preparation**

- Improve the Rejection Power (ACC)
- Enlarge the Block Size
- Optimize the Enclosure Box Dimension
- Details in [E19-0037-08]
- Improve the Time Resolution (MTOF)
- Both side read out
- Details in [E19-0032-08]

## Improve the Performance

_**Improve the Performance**_

**2- (a) Preparation**

- Improve the Rejection Power (ACC)
- Enlarge the Block Size
- Optimize the Enclosure Box Dimension
- Details in [E19-0037-08]
- Improve the Time Resolution (MTOF)
- Both side read out
- Details in [E19-0032-08]

**Can’t put PMT**

- PMT

## BESS-Polar II Structure Modification

_**BESS-Polar II**__** **__**Structure Modification**_

**2- (a) Preparation**

- BESS-Polar I

- BESS-Polar II

-  Shorten the height of the Solar-Panel
-  Allow the detector up-and-down in the Solar-Panel
-  Solar-Panel can still provide enough power for the detector

## 2- (a) Preparation

**2- (a) Preparation**

_**BESS-Polar II**__** **__**Structure Modification**_

## BESS-Polar II Improvements

_**BESS-Polar II**__** **__**Improvements**_

**2- (a) Preparation**

| Subject | BESS-Polar I | BESS-Polar II |
| --- | --- | --- |
| Magnet Cryogen Life | ~ 11 days | ~ 22.5 days |
| Data Storage Size | 3.5 TBytes | 16 TBytes |
| Drift Chamber Gas | ~ 10 days | ~ 20 days |
| Observation Time | 8.5 days | > 20 days |
| TOF PMT Housing | Resin Potting | Pressurized Housing |
| ACC Particle ID | Rejection ~ 630 | >> 1000 |
| MTOF Read Out | Single-end Read Out | Both-end Read Out |
| Solar Panel | 4 Stage (900W) | 3 Stage (675W) |

## Contents

_**Contents**_

-  Introduction
-  BESS-Polar II
-  Preparation
-  Flight
-  Status
-  Summary

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed

- Oct 26

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field

- Oct 26
- Nov 27

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test

- Oct 26
- Nov 27
- Nov 28

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready

- Oct 26
- Nov 27
- Nov 28
- Dec 1

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23

**McMurdo Station**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23

**McMurdo Station**

- Drift Chamber (JET) HV Problem.

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23

**McMurdo Station**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16

**McMurdo Station**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination

**McMurdo Station**

**Landing point**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21
- Feb 3

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination
- Data Recovery

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21
- Feb 3
- Feb 11

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination
- Data Recovery
- Last crew members left from Ice

**McMurdo Station**

**Landing point**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21
- Feb 3
- Feb 11

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination
- Data Recovery
- Last crew members left from Ice

**McMurdo Station**

**Landing point**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21
- Feb 3
- Feb 11

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination
- Data Recovery
- Last crew members left from Ice

**McMurdo Station**

**Landing point**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21
- Feb 3
- Feb 11

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination
- Data Recovery
- Last crew members left from Ice

**McMurdo Station**

**Landing point**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21
- Feb 3
- Feb 11

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination
- Data Recovery
- Last crew members left from Ice

**McMurdo Station**

**Landing point**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21
- Feb 3
- Feb 11

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination
- Data Recovery
- Last crew members left from Ice

**McMurdo (1830km)**

**South Pole (686km)**

**AGO2 (339km)**

**Patriot (398km)**

**Wais divide (770km)**

## BESS-Polar II Flight Trajectory

_**BESS-Polar II Flight Trajectory**_

**2- (b) Flight**

- Oct 26
- Nov 27
- Nov 28
- Dec 1
- Dec 23
- Jan 10
- Jan 16
- Jan 21
- Feb 3
- Feb 11

- First crew members were deployed
- First General Run with Magnetic Field
- Compatibility Test
- Flight Ready
- Launch!
- First Circle Completed
- Science Termination
- Balloon Termination
- Data Recovery
- Last crew members left from Ice

- ????

- BESS Detector will be recovered!

**McMurdo (1830km)**

**South Pole (686km)**

**AGO2 (339km)**

**Patriot (398km)**

**Wais divide (770km)**

## Contents

_**Contents**_

-  Introduction
-  BESS-Polar II
-  Preparation
-  Flight
-  Status
-  Summary

## BESS-Polar II Flight Status

**2- (c) Status**

**BESS-Polar II Trigger Rate**

**Climax neutron monitor**

**Solar wind speed**

-  Daily variation in cosmic-ray flux was clearly observed in BESS experiment.
-  It is surely correlated with solar wind activity and neutron monitor.
-  Daily variation of proton spectrum shape is useful for further study.

_**BESS-Polar II Flight Status**_

-  Observation time:        24.5 days
-  Cosmic-ray observed:                                 4700 M events
-  Recorded data size: 13.5 TBytes
-  Solar-Panel Status    ( M. Hasegawa, July 18 10:00 ~     [PSB1-0065-08])
- DAQ Status    (R. Orito [PSB1-0017-08 ])

## BESS-Polar II Magnet Status

_**BESS-Polar II Magnet Status**_

**2- (c) Status**

- Magnet life 22.5 days in ground -> ~ 25.5 days in flight
- 24.5 days science run with B-field was achieved!

**Ground**

**Flight**

## Detector Performances

_**Detector Performances**_

**2- (c) Status**

- Please Check The Poster Sessions!
- Outer Time Of Flight Counter
- Two PMTs were powered off
- Sustain full geometrical acceptance
- Time Resolution ~120 ps
- Details in [E19-0031-08]
- Aerogel Cherenkov Counter
- N.pe. 6.7 -> 11.3
- Particle ID (Rejection ~3000)
- Details in [E19-0037-08]
- Middle Time Of Flight Counter
- Time Resolution ~260 -360 ps
- Details in [E19-0032-08]

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

**Drift Chamber (JET) HV Problem.**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

- Event Display

## Drift Chamber Performance

_**Drift Chamber Performance**_

**2- (c) Status**

- Drift chamber still kept their performances after the HV problem!

## Contents

_**Contents**_

-  Introduction
-  BESS-Polar II
-  Preparation
-  Flight
-  Status
-  Summary

## BESS-Polar II Flight Summary

_**BESS-Polar II Flight Summary**_

**3) Summary**

|  | BESS-Polar I | BESS-Polar II |
| --- | --- | --- |
| Total Floating Time | 8.5 days | 29.5 days |
| Observation Time | 8.5 days | 24.5 days |
| Recorded Event | 900 M | 4700 M |
| Recorded Data Size | 2.1 TBytes | 13.5 TBytes |
| Trigger Rate | 1.4 kHz | 3.4 kHz |
| Live Time Fraction | 0.8 | 0.77 |
| Altitude | 37 ~ 39 km | 34 ~ 38 km |
| Residual Air Pressure | 4 ~ 5 g/cm2 | 4.5 ~ 8 g/cm2 |

## Don’t miss the    BESS-Polar II Results!

_**Don’t miss the    BESS-Polar II Results!**_

**3) Summary**

- Observed in Solar Minimum conditions

-   ~20 x statistics of the previous Solar Minimum.
-  Data Analysis is now in progress.

_**BESS Science Talk**_
- E19-0013-08
- John W Mitchell
- Friday, 18 July, 17:00 ~
- Room 520F

## BESS Presentation at the COSPAR 37th 

_**BESS Presentation at the COSPAR 37**__**th**__** **_

_**BESS Science Talk**_[E19-0013-08] John W Mitchell, Friday, 18 July, 17:00 ~ Room 520FThe BESS investigation of the origin of cosmic-ray antiprotons and search for cosmological antimatter
_**BESS Instrument Talk**_[PSB1-0065-08] Masaya Hasegawa, Friday, 18 July, 10:00 ~ Room 515BSolar-cell power system for the BESS Polar Experiment
_**BESS Poster Sessions**_ Room: 516B/C/D 517A/B, Date: 18-19 July 2008, 15:30 – 17:00[E19-0031-08] Performance of the BESS-Polar II Time-of-Flight Counter **Thomas Hams** for the BESS-Polar Collaboration ([E19-0031-08])
- [E19-0032-08] Development of a Thin Scintillator-Array Time-of-Flight Hodoscope with Fiber Bundle Readout onboard BESS-Polar II**Atsushi Horikoshi** and **Koji Yoshimura** for BESS-Polar Collaboration
- [E19-0037-08] Flight performance of BESS-Polar II Aerogel Chrenkov Counter**Kenichi Sakai** for the BESS-Polar Collaboratoin
- [E19-0054-08] The Cosmic ray 2H/1H and 3He/4He ratios measured from BESS in 2000 Solar Maximum.**K. C. Kim** for the BESS Collaboration
- Room: 517A/B, Date 17-18 July 2008, 15:30 – 17:00[PSB1-0017-08] Data Acquisition System for the BESS-Polar Experiment**Reiko Orito** for the BESS-Polar Collaboration