# Presentation: 340680

## Results from HiResand Observation of the GZK Suppression

- Results from HiResand Observation of the GZK Suppression

- Kai Martens
- High Energy Astrophysics Institute
- Department of Physics, University of Utah
- for the HiRes Collaboration

- HR1

- HR2

## Outline:

-  Short Introduction to Cosmic Rays
-  The HiRes Experiment
-  Monocular Observation:
-  Going to Extremes
-  Evidence for GZK Suppression
-  Stereo Observation:
-  Checks and Balances
-  HiRes Composition Measurement
-  Interpretation:
-  Ankle, Cutoff, and Cosmogenic Neutrinos
-  HiRes Neutrino Limits
-  In Search of the Sources:
-  Anisotropy
-  Correlations
-  Conclusions

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Cosmic Rays

- GeV

- TeV

- PeV

- EeV

- (m2 sr s GeV)-1

**10****-28**

**10****2**

- 1

- km2 y

- /

- Power laws for Flux:
-             J~E
- <3 PeV: =2.7
- ~3 PeV: Knee
- >3 PeV: =3.0

- Swordy Plot:

- knee

- ankle

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Air Shower Dimensions

**Fluorescence Detector:**
- 	_longitudinal_ profile
- 	throughout atmosphere
**Ground Array:**
- 	_transverse_ profile
- 	at ground level

- _Cosmic Ray showers_
-  start at ~ 15 km above ground
-  span a couple of km across
-  hundreds of billions of particles

- thick water tanks  thin scintillators

**10****19**** **
**eV**

- (e/m + )

- (e/m only)

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## The HiRes Experiment:

**12.6 km apart**

- HR2: 12/1999
- 42 mirrors
- 3****-31**** elevation
- FADC (100ns)

**Dugway**
**Proving**
**Grounds**

- HR1: 5/1997
- 19 mirrors
- 3****-17****elevation
- Sample&Hold

_**HiRes on DPG:**_

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## HiRes Optics:

- Mirror surface 5.1 m2
- Field of view: 16**** x 14****

- _Camera:_
- 16 x 16
- PMT
- each sees
- 1**o** x 1**o**
- in sky

- UV filter !!!
- (protecting PMTs)

- low resolution
- high speed

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## HiRes:  Stereo!!!

**July 11, 1999; Energy: 19 EeV**

- Light Propagation:
_*Atmosphere*_

**HR1**

**HR2**

**HR2**

**HR1**

- Dugway Proving Ground

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## The Collaboration:

**S. BenZvi, J. Boyer, B. Connolly, C.B. Finley, B. Knapp, E.J. Mannel, A. O’Neill, M. Seman, S. Westerhoff**
**Columbia University**
**J.F. Amman, M.D. Cooper, C.M. Hoffman, M.H. Holzscheiter, C.A. Painter, J.S. Sarracino, G. Sinnis, T.N. Thompson,  D. Tupa**
**Los Alamos National Laboratory**
**J. Belz, M. Kirn**
**University of Montana**
**J.A.J. Matthews, M. Roberts**
**University of New Mexico**
**D.R. Bergman, G. Hughes, D. Ivanov, L. Perera, S.R. Schnetzer, L. Scott, S. Stratton, G.B. Thomson, A. Zech**
**Rutgers University**
- N. Manago, M. Sasaki
**University of Tokyo**
**R.U. Abbasi, T. Abu-Zayyad, G. Archbold, K. Belov, A. Blake, O. Brusova, Z. Cao, W. Deng, W. Hanlon, P. Huentemeyer, C.C.H. Jui, **
**E.C. Loh, K. Martens, J.N. Matthews, D. Rodriguez, K. Reil, J. Smith, P. Sokolsky, R.W. Springer, B.T. Stokes, S.B. Thomas, L. Wiencke**
**University of Utah**
**Z. Cao, B. Zhang, Y. Zhang, Y. Yang**
**IHEP Bejing**

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Challenge: (Mono) Reconstruction

- light curve
- +
- atmosphere
- =
- energy

- Reconstruction
- steps:
- 1. shower detector
-     **plane**
- 2. Shower **axis**
-     (full geometry)
- 3. fluorescence
-     **light** curve

- (FADC !!!)

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## HiRes Monocular Spectra

- flux x E3

- HR1:  longer exposure
- 	 high energy
- HR2:  larger elevation coverage
- 	 low energy

- energy scale uncertainties:
-  missing energy	  5%
-  energy loss rate	10%
-  fluorescence yield	  6%
-  atmospheric conditions  4%
-  photometric calibration	10%
-  total (energy):	17%
-   flux uncertainty:	30%
- 	   (@ =2.8)

-           data:
- HR1:    5/97-6/05
- HR2:  12/99-8/04

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## HR1:  Aperture Verification - Data vs. MC

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## HR2:  Aperture Verification - Data vs. MC

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

##   GZK Suppression: ?  !!

- Old plots:
- AGASA
- AGASA (E–20%)

- avoid double counting:
- remove HR1 events that also
- are in the HR2 data set

- Broken power-law fits:
- a.) one vs. two breakpoints:
- 	2 reduced by 23.4
- 	 4.5
- b.) compare measured data
- 	to red line extrapolation:
- 	expect:	  39.9
- 	observe: 13
- 	 4.8  (P=7x10-7)

- Quacks like duck, don’t it?

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Stereo Observation

- full stereo analysis ongoing; shown: geometry from HR1/HR2plane intersect,
-                                                                     light curve from HR2 data only:

- stereo advantages: geometry constraint (!!!), light balance check on atmosphere

- energy balance:

**X****max**** resolution: 30g/mc****2**

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Composition from Stereo Data

- Xmax distributions:

- data
- vs.
- proton

- data
- vs.
- iron

- Xmax [g/cm2]

- Xmax [g/cm2]

- 18

- 20

- log10(E/eV)

- Fe + p   |  (mostly) p

- data: HR
- prototype

- HiRes stereo
- data: ~ 80% p

- MC: p

- MC: Fe

- galactic

- extra-galactic

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Interpretation of HiRes monocular CR:

- Doug Bergman, Rutgers
- (following Berezinsky)

- Fit interprets spectrum
- in terms of
**extragalactic protons**
- that traveled from
**cosmological sources**

- changed interpretation of ankle:

- galactic/extragalactic transition:    composition change  vs. slope change

**p+********  ********  ********(1232)  ********  ********+N**

- ****  **** + ********
- 	****  e**** + ******e** + ********

- composition change

- slope change

- p+  p+e++e-

-  redshift

- energy 

-   flux 

- propagation:
- protons
- only

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## HiRes Composition Guided Fits   flux

- HiRes Composition Guided Fits  **** flux

- _source model:_
- all sources inject with E****
-   = 2.42
- uniform with redshift
- evolution (1+z)m
-  m = 2.46

- future: astronomy inspired
- redshift evolution

- composition as
- measured !

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## The HiRes Neutrino Limits:

- 90% CL, uncertainty
- MC statistics only

- MC injection: E-2 spectrum

- e limits (no topography):
- 1018 – 1019:   3820 ±120
- 1019 – 1020:   3260   ±80
- 1020 – 1021:   4250 ±100

-  event distinguishing features:
-   - horizontal !!!
-   - close to ground

- target mass:	rock
- detector volume:	air

****e  LPM
********   ****-lepton

-  limits:
- 1018 – 1019:     420-20+25
- 1019 – 1020:   1340-110+140
- 1020 – 1021: 29400-8900+22100

-  fluxes as derived from HR spectrum fit

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## MC: Topology at Work

-  interaction points for  decaying above ground:

**90**

**95**

-  zenith
- angle in
- HR system:

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Anisotropy and Clustering

- HR2 *Sky Map:*

-  non-uniform exposure...
-      use MC & on-time database
-      to estimate uniform exposure

*Point Sources:*
- _AGASA for E > 40 EeV_:
-     5 doublets, 1 triplet
- _HiRes stereo +AGASA_:
-     28% of MC > triplet
- HiRes: E > 30 EeV:
-      triplet + 1

*Looking for Accelerators:* BL lac
- Tinyakov, Tkachev, Gorbunov analysis:
- 	Vernon 9th, m<18, AGASA+Yakutsk:
- 	E>48 (24) EeV  P=10-4
- 	Vernon 10th, BL criteria differ, HiRes:
- 	E>10 EeV  P=10-3
- HiRes analysis (all events): 0.02%
-  the jury is still out: _more data_

- _Findings:_
-  no global dipole
-  deficit at Galactic Anticenter??? (3.4)

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Fixed Target Experiment @ 31018eV

- mean
- energy:
- ~ 1018.5 eV

- “protons”
- selected

**X****max******

- Data:

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Now Commissioning:  Telescope Array

**Now Commissioning:  Telescope Array**

**T**

**A**

- 3 x 120 deg
- fluorescence
- telescopes

- MCCRC
- Delta, UT
- 2h from SLC

- 512 x 3m2
- scintillator
- array

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## Conclusions

-  HiRes has finished taking data
-  HiRes has changed the cosmic ray (CR) landscape:
- - extragalactic CR mostly protons
- - GZK suppression present in data  + resonance
-  ankle likely e+e-, not transition to extragalactic...
- 	 spectral features important  TALE
-  HiRes finds no significant UHE-CR anisotropies
-  HiRes finds no significant UHE-CR clustering
-  Correlations with astrophysical sources: jury still out
-  Ultra High Energy (UHE) CR research is alive in Utah:
-  Come and join our efforts for TA/TALE
-               www.telescopearray.org
- 		kai@physics.utah.edu

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007

## HiRes & Auger Limits

- Kai Martens, University of Utah, @ ISMD

- August 7, 2007