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MP BACH M ulti P ixel B alloon-borne A ir CH erenkov Detection of Iron Cosmic Rays Using Direct Cherenkov Radiation Imaged with a High Resolution Camera University of Delaware Paul Evenson , John Clem, Jamie Holder, Katie Mulrey and Dave Seckel. PDQ BACH Fort Sumner 1998. POD.

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slide1

MP BACHMultiPixelBalloon-borne Air CHerenkovDetection of Iron Cosmic Rays Using Direct Cherenkov Radiation Imaged with a High Resolution CameraUniversity of DelawarePaul Evenson, John Clem, Jamie Holder, Katie Mulrey and Dave Seckel

slide2

PDQ BACH

Fort Sumner 1998

POD

slide3

Current knowledge of the iron spectrum

Energy spectrum of Iron cosmic rays multiplied by E2.5 from different observations. JACEE and RUNJOB, emulsion instruments, are a compilation of many balloon flights. CRN was conducted on the space shuttle. CREAM, ATTC and TRACER are balloon payloads flown from Antarctica and Sweden. BACH payload was flown from Ft Sumner. Soodpioneered the BACH technique. KASKADE (two different interaction models) and EAS-TOP (upper and lower limits) are air shower data. HESS data (two different interaction models) are ground level observations of Cerenkov light imaging.

slide5

As the particle penetrates into denser air, the Cherenkov angle and intensity increase.

First photons are emitted just on the axis defined by the particle path, but subsequent photons lie further and further from the axis when they reach any given depth in the atmosphere forming a circular spot or “pool” of light .

This trend continues until the particle is roughly two scale heights (15 km) above an observer, when proximity finally wins out.

corsika simulation
CORSIKA Simulation
  • Simulates detailed particle propagation and generates CK photons in the atmosphere
idealized detector images 500tev fe
Idealized Detector Images, 500TeV Fe

Camera locations in light pool

Non-

Interacting

Interacting

slide10

Deflection in the Earth’s Magnetic Field

* Energy & Charge dependence *

slide16

With only the DCs,

reconstruct trajectory

εc is the CK emission vector as viewed from Camera 1 and 2

θcH

Directional cosine observations from the camera

and camera location on the gondola

z

S

θcL

Pathlength to emission point

εca

εcb

y

x

θ

φ

(x2,0)

(x1,0)

(xo,yo)

Camera 1 event plane

Camera 2 event plane

Intersection of Plane C1 and C2 forms a line that lies along the particle trajectory

cross product of these two normal C1 and C2 vectors gives a vector which is perpendicular to both of them and which is therefore parallel to the line of intersection of the two planes. So this cross product will give a direction vector for the line of intersection.

Set z=0 and solve for x and y

slide17

Particle trajectory passes through the x,y plane at location xo,yo

The particle incident angle with respect to z is θ and φ is the polar

θc= Cerenkov angle which is a function of z (air density)

Sis the trajectory straight path-length from the x-y plane intersection to the CK emission point as viewed by camera 1

No Magnetic Field

z

S

θc

Pathlength to emission point

εc

y

x

θ

φ

(x2,0)

(x1,0)

(xo,yo)

It can be shown that S is related to the other quantities as

εc is the CK emission vector as viewed from Camera 1

y

Camera 2

Camera 1

x

x1

z

slide18

If the steepening at the cosmic ray knee is caused by a magnetic rigidity dependent mechanism, as a result of an acceleration process limited in a rigidity dependent manner or rigidity dependent propagation, there should be systematic changes in the cosmic ray composition through this region.

It is difficult to see how SN could accelerate protons to energies much beyond ~1015eV/particle. Heavier cosmic rays, for example iron nuclei, could reach energies over an order of magnitude higher than this via the same mechanism.

The objective of this project is to improve our knowledge of the Iron Flux from 5x103 to 3x106GeV

slide19

Explicitly determine the relationship for

the x,y crossing point at z=0

θcH

z

S

θcL

Pathlength to emission point

εca

εcb

y

x

θ

φ

(x2,0)

(x1,0)

(xo,yo)

slide20

Directional cosine observations from the camera

and camera location on the gondola

θca

z

S

θcb

Pathlength to emission point

The trajectory vector S has been determine and is then used to calculate the Cerenkov angle at each intersection point

εca

εcb

y

x

θ

φ

(x2,0)

(x1,0)

(xo,yo)

The index of refraction at each intersection altitude point must be determined to calculate the energy

slide21

Altitude (km)

Altitude (km)

ThetaC (degrees)

Altitude (km)

slide22

Results

The calculated energy uses only the directional cosines, camera location and atmospheric model

slide24

Camera 1 Image

Camera 2 Image

z

degrees

degrees

y

degrees

degrees

x

θ

φ

(x2,0)

(x1,0)

(xo,yo)

Example MPBACH Simulated Event Cartoon

slide25

Cherenkov Light Distribution from Interacting and Non-Interacting Primaries

Non-interacting Vertical Iron, 1PeV

Cherenkov Total Light Output, 1PeV

H

He

Fe

Si

O

Peaks indicate the non-interaction events

slide26

As the particle penetrates into denser air, the Cherenkov angle and intensity increase.

First photons are emitted just on the axis defined by the particle path, but subsequent photons lie further and further from the axis when they reach any given depth in the atmosphere forming a circular spot or “pool” of light .

This trend continues until the particle is roughly two scale heights (15 km) above an observer, when proximity finally wins out.

75km

Altitude (km)

35km

-8

0

8

Distance from Axis (m)

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