antiprotons in the cosmic radiationresearch.kek.jp/group/zeus/nikko/nikko-5-pdf/nozaki.pdf ·...
TRANSCRIPT
-
2004.11.5 物質の創生と発展 1
Antiprotons in the cosmic radiation-- A brief history and some recent results of BESS --
Mitsuaki NOZAKI(Kobe Univ.)
( ISAS/ KEK/ Kobe/ Maryland/ NASA/ Tokyo)
Antiprotons in the cosmic radiation
-- A brief history and some recent results of BESS --
Mitsuaki NOZAKI
(Kobe Univ.)
( ISAS/ KEK/ Kobe/ Maryland/ NASA/ Tokyo)
物質の創生と発展
We have been mesuring cosmic ray antiprotons for more than 10 years
And still trying to do a longer observation at Antarctica.
Today I am going to talk why there are so many things to measure
about antiprotons.
Antiprotons in 1980s
Buffignton et al. reported
a very high flux that motivated many speculations on its origin such as photino annihilation and
various propagation models.
物質の創生と発展
苦節6年
艱難辛苦を乗り越えて
物質の創生と発展
Balloon specific issues:
Weight & size
Power supply
Heat dissipation
Telecommunication
Mechanical robustness
One chance per year
物質の創生と発展
物質の創生と発展
With better TOF timing resolution
物質の創生と発展
BESS '97
With additional aerogel Chrenkov counter
物質の創生と発展
Detection → Spectrum
物質の創生と発展
Before → After
物質の創生と発展
物理のお話し
物質の創生と発展
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
Galactic secondary
Atmospheric secondary
Interstellar primary proton
Solar-modulated "primary" proton
~ 5 g/cm2 @ balloon altitude
lesc ~ 10 g/cm2
c
c
物質の創生と発展
Our final goal is to find some antirptons produced by these exotic processes;
the evaporation of primordial black holes or the annihilation of dark matter particles.
However, most of the antiprotons are considered to be produced in our galaxy
by this normal hadronic interactions.
After the production by this process, antirprotons go on a long journey.
They travel through the galaxy for several tens of million years before reaching the solar system.
In the heliosphere, antiprotons are disturbed by the expanding magnetic irregularities.
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
Galactic tertiary
Atmospheric tertiary
Galactic secondary
Solar-modulated galactic secondary (+tertiary)
+ Atmospheric secondary (~20% @ 5g/cm2)
c
c
物質の創生と発展
In the atmosphere, antiprotons interact with air nuclei by this hadronic interaction.
And finally some of the survivors are detected by BESS or any other cosmic ray detectors.
The secondary-produced galactic antirprotons may also interact with istellar medium.
They may lose energy by inelastic interactons or may be completely lost by annihilations.
We call them tertiary antiprotons.
So, if we want to find something news, all the ordinary processes must be well-known.
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
Galactic secondary
Atmospheric secondary
Interstellar primary proton
Solar-modulated "primary" proton
~ 5 g/cm2 @ balloon altitude
lesc ~ 10 g/cm2
c
c
物質の創生と発展
Let me start with the energy spectrum of the primary protons.
JET/IDCNmax2852pts
sx200150mm
ODCLtrack0.8 1.6m
MDR2001400GV
BESS-98 BESS-TeV
JET/IDC
ODC
物質の創生と発展
To measure high enrgy protons up to several hundred GeV, we have refurbished the tracking system.
We have installed a new jet-type drift chamber with better performance.
We added a pair of outer drift chambers outside the solenoid.
The MDR has been increased from 200 to 1400 GV.
The tracking resolution is much better than the previous BESS detector.
Phys. Lett. B594 (2004) 35-46
Proton Spectrum
At high energies (>30 GeV)
1 < E < 540 GeV
He nuclei have also been measured
in the energy range btw. 1 and 250 GeV/n.
物質の創生と発展
The energy spectrum was measured up to 540 GeV.
At high energies up to 100 GeV, the flux is consistent with our previous measurement and also consistent with AMS.
However, in the low energy region, the solar modulation can not be neglected.
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
Galactic secondary
Atmospheric secondary
Interstellar primary proton
Solar-modulated "primary" proton
~ 5 g/cm2 @ balloon altitude
lesc ~ 10 g/cm2
c
c
物質の創生と発展
We have measured the proton spectra almost annually.
Solar modulation
in preparation
At low energies
(Eth< E < ~20 GeV)
D(flux) ~ 10 - 40%
物質の創生と発展
From these measurements, from 1997 to 2002, we can derive an interstellar spectrum,
which is used to calculate the galactic antirprotons.
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
Galactic tertiary
Atmospheric tertiary
Galactic secondary
Solar-modulated galactic secondary (+tertiary)
+ Atmospheric secondary
c
c
物質の創生と発展
I move on to antirprotons.
Antiproton at
solar minimum
secondary dominant
Phys. Rev. Lett. 84 (2000) 1078
galactic tertiary ?
Measurement ~ Calculation
The majority is galactic secondary
物質の創生と発展
This is the spectrum observed in the solar minimum period.
Due to the production kinematics and the sharply decreaseing primary proton spectrum,
the secondary antiproton spectrum has this characteristic peak around 2 GeV.
The BESS data show that the majorityof the cosmic ray antiprotons is secondary.
In addition to the shape, the absolute value of the flux agrees well with these calculations.
That means our propagation model is basically OK.
However, in the low energy region, there is some diffrence between calculations.
The low statistics of the data can not tell which model is better.
We first investigated the solar modulation effect on the antiproton spectrum.
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
Galactic tertiary
Atmospheric tertiary
Galactic secondary
Solar-modulated galactic secondary (+tertiary)
+ Atmospheric secondary
c
c
物質の創生と発展
Solar modulation
Astropart.Phys. 16 (2001) 121 & Phys.Rev.Lett. 88 (2002) 051101-1
The drift model explains the ratio, but still needs to be fine-tuned to reproduce the abolute. flux.
物質の創生と発展
This busy plot shows a compilation of our antiproton measurements sinxe 1993.
The statistical error is large but we can see clearly the modulation effect in the peak region.
If we take the ratio with the proton flux, the ratio is well-reproduced by a dirft model rather tahn a spherical model.
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
Galactic secondary
Atmospheric secondary
Interstellar primary proton
Solar-modulated "primary" proton
~ 5 g/cm2 @ balloon altitude
lesc ~ 10 g/cm2
c
c
物質の創生と発展
I will show you some new results about the atmospheric antiprotons.
I want to mention that these 2 production processes are similar to each other except for target particles.
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
Purely atmospheric antiprotons have been measured below geomagnetic cutoff.
Rcutoff (GV) / Ek (GeV)xair (g/cm2)
Ft. Sumner (2001)4.2 (3.4)4~26
Norikura (1999)11.2 (10.3)~742
KEK (1997)11.4 (10.5)~1000
c
c
物質の創生と発展
We have measured atmospheric antiprotons at 3 different locations.
In 1999, we carried the apparatus to the top of Mt.Norikura.
Antiproton@乗鞍
Phys.Lett. B577 (2003) 10
H=2770 m
35 km from Kamioka
110 antiproton candidates
Tsukuba
Norikura
物質の創生と発展
Norikura is near the famous Kamioka mine.
Near the mountain top, there is a cosmic ray obseravatory.
We have detected 110 antiprotons.
PBH
To search for novel sources of antiprotons, known effects should be "well-known",
Purely atmospheric antiprotons have been measured below geomagnetic cutoff.
Rcutoff (GV) / Ek (GeV)xair (g/cm2)
Ft. Sumner (2001)4.2 (3.4)4~26
Norikura (1999)11.2 (10.3)~742
KEK (1997)11.4 (10.5)~1000
c
c
物質の創生と発展
In 2001, we went to Ft. Sumner, New Mexico.
BESS-2001
Flight at Ft.Sumner, NM
4 g/cm2
26 g/cm2
Phys.Lett. B564 (2003) 8
Rcutoff= 4.2 GV
物質の創生と発展
In this flight, the balloon lost altitude after reaching the floating altitude.
The air thickness increased from 4 g to 26 g in 12 hours.
The geomagnetic cutoff is clearly seen in this proton spectra.
Below this cutoff antiprotons are purely atmospheric.
物質の創生と発展
Antiprotons are identified by the time-of-flight measurement and the aerogel chrenkov counters
with the refractive index of 1.022.
e/m contamination
Aerogel Cherenkov Counter
n=1.022
Rth(p) = 4.4 GV
Eth(p) = 3.6 GeV
eproton= 95.40.3%
Rejection factor = 7610
Contamination is largest
at the highest energy
~ 5% (Ft.Sumner)
~20% (Tsukuba)
物質の創生と発展
This distribution showsthe light output from the aerogel counter for the relativistic particles.
The rejection factor for light particles is 7610 while keeping the efficiendy at 95%.
Tsukuba (970-1010 g/cm2)
25 antiproton candidates
(0.4 - 3.4 GeV)
Ft.Sumner (4 - 26 g/cm2)
156 antiproton candidates
(0.2 - 3.4 GeV)
Atmospheric antiprotons
物質の創生と発展
We have detected 156 antiprotons below geomagnetic cutoff.
We also measured at KEK, Tsukuba in 1997.
At KEK, we have detected 25 antiprotons.
I sprod +sinel
II sprod+sinel (ann. only)
III sprod+sinel (ann. only)
IV sprod+sinel
V sprod +sinel (ann. only)
s(I) is based on S.A.Stephens, Astropart..Phys. 6 (1997) 229
s(V) is based on C.Y.Huang, PhD Thesis & Phys. Rev. D68 (2003) 053008
Model I~V : Calculated by K.Yamato, PhD Thesis
Model Comparison
4-26 g/cm2
994 g/cm2
I
II
III
IV
V
III
II
I
IV
V
物質の創生と発展
We compared our measuremets with some models.
Basically, we followed the calculation of Stephens published in 1997.
We used 2 different production cross sections and 2 diffrent ineleastic cross sections.
One is taken from Stephens; with smaller production cross section and larger inelastic cross setion,
and the other from Huang; with larger production cross section and smaller inelastic cross section,
which includes only the annihilation.
I do not describe the details of their models.
The essential difference is the energy distribution of tertiary antiprotons.
Stephens assumed a flat distribution.
Huang considers only annihilation, so the tertiary antiproton has delta-function like distribution.
The other models assumes some combinations of their cross sections.
If you look at this part, the smaller cross section seems to be better,
but if you look at the low energy region, it seems that the contribution fromt the annihilation is small.
Atmospheric antiprotons
at balloon altitude
at mountain
at ground
BG to galactic antiprotons
物質の創生と発展
This shows our 3 measurements and 2 calculations.
The smaller cross section from Stephens plus Huang's annihilation-only interaction seems to explain the data.
The systematic error we quote for the background subtraction in our previous publications
is shown by green shade which lies between model I and III.
The subtraction we made is based on the intermediate cross sections.
将来計画
Primary proton/Helium flux
Galactic propagation
Sloar modulation
Atmospheric interaction
“普通のプロセス”の理解が深まった
もっと統計を!
物質の創生と発展
物質の創生と発展
BESS-Polar
Technical Flight at Ft. Sumner
Assembly at GSFC/NASA
物質の創生と発展
Nozaki Mitsuaki�Nozaki_Nikko.ppt�
-
Antiprotons in 1980s
Buffignton et al. reported a very high flux that motivated many speculations on its origin such as photino annihilation and various propagation models.
2004.11.5 物質の創生と発展 2
-
苦節6年
艱難辛苦を乗り越えて
2004.11.5 物質の創生と発展 3
-
2004.11.5 物質の創生と発展 4
m = Rze 1
β 2−1 Balloon specific issues:• Weight & size
• Power supply• Heat dissipation• Telecommunication• Mechanical robustness• One chance per year
-
2004.11.5 物質の創生と発展 5
-
2004.11.5 物質の創生と発展 6With better TOF timing resolution
-
2004.11.5 物質の創生と発展 7
BESS '97
With additional aerogel Chrenkov counter
-
2004.11.5 物質の創生と発展 8
Detection → Spectrum
-
2004.11.5 物質の創生と発展 9Before → After
-
物理のお話し
2004.11.5 物質の創生と発展 10
-
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
Galactic secondary Atmospheric secondary
p + pσ⎯ → ⎯ p n ( )+ X vs. p + N air
σ⎯ → ⎯ p + X
~ 5 g/cm2 @ balloon altitudeλesc ~ 10 g/cm2
Interstellar primary proton Solar-modulated "primary" proton
2004.11.5 物質の創生と発展 11
-
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
p + p σ⎯ → ⎯
p n ( )+ XX
⎧ ⎨ ⎩
vs. p + N airσ⎯ → ⎯
p + XX
⎧ ⎨ ⎩
Galactic tertiary Atmospheric tertiary
Galactic secondary Solar-modulated galactic secondary (+tertiary)
2004.11.5 物質の創生と発展 12+ Atmospheric secondary (~20% @ 5g/cm2)
-
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
p + pσ⎯ → ⎯ p n ( )+ X vs. p + N air
σ⎯ → ⎯ p + X
Galactic secondary Atmospheric secondary
Interstellar primary proton Solar-modulated "primary" proton
~ 5 g/cm2 @ balloon altitudeλesc ~ 10 g/cm2
2004.11.5 物質の創生と発展 13
-
2004.11.5 物質の創生と発展 14
JET/IDC Nmax 28 → 52 ptsσx 200 → 150 µm
ODC Ltrack 0.8 → 1.6 mMDR 200 → 1400 GV
JET/IDCODC
BESS-98 → BESS-TeV
-
2004.11.5 物質の創生と発展 15
Proton Spectrum
1 < E < 540 GeV
At high energies (>30 GeV)
F = ΦE k−γ (m2 ⋅ sr ⋅ sec ⋅ GeV)−1
Φ = 1.37 ± 0.06 ± 0.11( )×10−4
γ = 2.732 ± 0.011± 0.019
He nuclei have also been measuredin the energy range btw. 1 and 250 GeV/n.
Phys. Lett. B594 (2004) 35-46
-
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
p + pσ⎯ → ⎯ p n ( )+ X vs. p + N air
σ⎯ → ⎯ p + X
Galactic secondary Atmospheric secondary
Interstellar primary proton Solar-modulated "primary" proton
~ 5 g/cm2 @ balloon altitudeλesc ~ 10 g/cm2
2004.11.5 物質の創生と発展 16
-
Solar modulation
At low energies(Eth< E < ~20 GeV)
∆(flux) ~ 10 - 40%
in preparation
2004.11.5 物質の創生と発展 17
-
2004.11.5 物質の創生と発展 18
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
p + p σ⎯ → ⎯
p n ( )+ XX
⎧ ⎨ ⎩
vs. p + N airσ⎯ → ⎯
p + XX
⎧ ⎨ ⎩
Galactic tertiary Atmospheric tertiary
Galactic secondary Solar-modulated galactic secondary (+tertiary)
+ Atmospheric secondary
-
2004.11.5 物質の創生と発展 19
Antiproton atsolar minimum
secondary dominant
Phys. Rev. Lett. 84 (2000) 1078
Measurement ~ Calculation ⇓
The majority is galactic secondary
galactic tertiary ?
-
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
p + p σ⎯ → ⎯
p n ( )+ XX
⎧ ⎨ ⎩
vs. p + N airσ⎯ → ⎯
p + XX
⎧ ⎨ ⎩
Galactic tertiary Atmospheric tertiary
Galactic secondary
2004.11.5 物質の創生と発展 20
Solar-modulated galactic secondary (+tertiary)
+ Atmospheric secondary
-
Solar modulation
2004.11.5 物質の創生と発展 21Astropart.Phys. 16 (2001) 121 & Phys.Rev.Lett. 88 (2002) 051101-1
The drift model explains the ratio, but still needs to be fine-tuned to reproduce the abolute. flux.
-
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
and to gain the statistics we go to Antarctica.
p + pσ⎯ → ⎯ p n ( )+ X vs. p + N air
σ⎯ → ⎯ p + X
Atmospheric secondaryGalactic secondary
~ 5 g/cm2 @ balloon altitudeλesc ~ 10 g/cm2
Interstellar primary proton Solar-modulated "primary" proton
2004.11.5 物質の創生と発展 22
-
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
2004.11.5 物質の創生と発展 23
Rcutoff (GV) / Ek (GeV) xair (g/cm2)Ft. Sumner (2001) 4.2 (3.4) 4~26Norikura (1999) 11.2 (10.3) ~742KEK (1997) 11.4 (10.5) ~1000
Purely atmospheric antiprotons have been measured below geomagnetic cutoff.
-
2004.11.5 物質の創生と発展 24
Tsukuba
Norikura
Antiproton@乗鞍
Phys.Lett. B577 (2003) 10
H=2770 m
35 km from Kamioka
110 antiproton candidates
-
PBHχ
χ
p
To search for novel sources of antiprotons, known effects should be "well-known",
2004.11.5 物質の創生と発展 25
Rcutoff (GV) / Ek (GeV) xair (g/cm2)Ft. Sumner (2001) 4.2 (3.4) 4~26Norikura (1999) 11.2 (10.3) ~742KEK (1997) 11.4 (10.5) ~1000
Purely atmospheric antiprotons have been measured below geomagnetic cutoff.
-
BESS-2001Flight at Ft.Sumner, NM
Rcutoff= 4.2 GV
4 g/cm2
26 g/cm2
Phys.Lett. B564 (2003) 82004.11.5 物質の創生と発展 26
-
2004.11.5 物質の創生と発展 27
-
2004.11.5 物質の創生と発展 28
e/µ contamination
Aerogel Cherenkov Counter
n=1.022Rth(p) = 4.4 GVEth(p) = 3.6 GeV
εproton= 95.4±0.3%Rejection factor = 7610
Contamination is largestat the highest energy~ 5% (Ft.Sumner)~20% (Tsukuba)
-
Atmospheric antiprotons
Tsukuba (970-1010 g/cm2)
25 antiproton candidates(0.4 - 3.4 GeV)
Ft.Sumner (4 - 26 g/cm2)
156 antiproton candidates(0.2 - 3.4 GeV)
2004.11.5 物質の創生と発展 29
-
2004.11.5 物質の創生と発展 30
I σprod +σinelII σprod+σinel (ann. only)III σprod+σinel (ann. only)IV σprod+σinel V σprod +σinel (ann. only)
I
II
III
IV
V
III
II
I
IV
V
σ(I) is based on S.A.Stephens, Astropart..Phys. 6 (1997) 229σ(V) is based on C.Y.Huang, PhD Thesis & Phys. Rev. D68 (2003) 053008Model I~V : Calculated by K.Yamato, PhD Thesis
Model Comparison
4-26 g/cm2 994 g/cm2
-
2004.11.5 物質の創生と発展 31
Atmospheric antiprotonsat balloon altitudeat mountainat ground
BG to galactic antiprotons
-
将来計画
• Primary proton/Helium flux• Galactic propagation• Sloar modulation• Atmospheric interaction
• “普通のプロセス”の理解が深まった• もっと統計を!
2004.11.5 物質の創生と発展 32
-
2004.11.5 物質の創生と発展 33
-
2004.11.5 物質の創生と発展 34
BESS-Polar
Technical Flight at Ft. Sumner
Assembly at GSFC/NASA
Antiprotons in the cosmic radiation-- A brief history and some recent results of BESS --将来計画