GP300 cosmic-ray candidates to be shown at ICRC 2025: Selection¶

This page contains the first list of cosmic-ray (CR) candidates detected by GP300.

Selection criteria¶

The criteria used to select the CR candidates was developed by Jolan Lavoisier and Xishui Tian. Some of the entries below mention criteria by both Jolan and Xishui; in these cases, both criteria are applied, and the most selective criterion is chosen.

The data analyzed was collected by GP300 from the beginning of December 2024 to the end of March 2025.

Note about z-polarization from Jolan (17/05/2025): I checked all the candidates' channel 4, and found that they all are Z-channel

The selection criteria are:

1. Reconstruction quality
   Jolan: planar wave front (PWF) error cut (reconstructed errors on PWF must be ≤ 0.5 degrees, slides 5-6 in https://forge.in2p3.fr/attachments/436203). Arsene has written a code that allows me to compute an angular error over the direction arrival given by his functions. You can find these functions at the following link: https://github.com/arsenefer/PWF\_reconstruction/tree/main .
   Xishui: chi2<300 of the spherical wave front (SWF). The SWF reconstructs the position of the shower core in 3d (in cartesian coordinates, usually with the origin set at the DAQ center)
2. Clustering cut
   Jolan: PWF argument, removing events that fall within ± 5 degrees and ± 5 seconds. "PWF argument" means I base myself of PWF-given direction arrival of an event (event A). I then look if any other event end up in a 10 sec time window around the detection time of A, and in a 10 degrees window around its direction arrival. Xishui uses a the SWF-given direction of arrival, and his windows are 400 seconds time-wise and 60 degrees in azimuth and 10 degrees in zenith direction-wise.
   Xishui: directions from the SWF, ±30deg and ± 200s)
3. Polarization cut [ Jolan ]
   Using the traces to reconstruct a polarisation for each antenna in an event, and cutting on the value of the median. I cut at 0.3. This value corresponds to the scalar product of the direction of the polarisation reconstructed in each antenna and the direction of the magnetic field. For CR, this scalar product should be null. I will soon have a value motivated by precise statistics, but 0.3 is a good estimate already.
4. Multiplicity cut
   The number of antennas must be ≥ 5
5. Arrival cut
   Jolan: PWF, the reconstructed zenith angle must be below 60 degrees:
   Xishui: same, but from SWF, which depends on the choice of (0,0)).
6. Event time cut
   Use events after 2024.12.01 (remove DUs with bad GPS timings, but should be useless for CD)
7. No high RMS values for the chX and chY [*Xishui*]
   RMS_X(50-80MHz) < 2E-3[V], RMS_X(160-225MHz) < 1E-3
   RMS_Y(50-80MHz) < 2E-3[V], RMS_Y(160-225MHz) < 3E-3
   Values are empirical drawn from the 2025Mar data.
8. SNR cut [ Xishui ]
   The SNR of chY should be greater than 5 for all DUs.
9. Remove DU1032 and DU1049 [*Xishui*]
   This is because DU1032 and DU1049 have too few/many triggers, which could result from the self-generated noise or the HW glitch. (from 2025Mar data)
10. Visual cut of the spread of the footprint [*Jolan*]
    A good candidate footprint should have a ellipse shaped-footprint i.e. triggered antennas that are too far apart deter me from counting an event as a cosmic ray (especially if there are too many DUs triggered, a footprint of a CR is hardly that large)
11. visual cut of the quality of the trace (wrt to simulations) [ Jolan ]
    CR traces are easily identifiable, compared to most of the noise. Mine and plane noise are usually too long and/or too "pointy" to be CRs (attached two examples of such traces:
    
    

List of selected events¶

All events are from GP300.

Download these data in a plain text file: https://forge.in2p3.fr/attachments/442823

In the table below, struckthrough data was eliminated after the CR candidate list was first formed. Those data only appear in the table below, not in the downloadable file above. The following former CR candidates were removed:

• 20250109_020738 - 28

Event name	run-no_time	Entry
CR0	20241209_054702	820
CR1	20241215_180709	0
CR2	20241219_162205	0
CR3	20241220_033050	5
CR4	20241220_043936	13
CR5	20241222_054623	122
CR6	20241224_133033	19
CR7	20241226_113611	68
CR8	20241226_114408	37
CR9	20241229_084801	254
CR10	20250102_003735	2
CR11	20250102_013241	2
CR12	20250102_021724	38
CR13	20250102_073620	117
CR14	20250102_133014	1
CR15	20250103_013446	0
CR16	20250105_041755	78
- - -	20250109_020738	28
CR17	20250111_133346	46
CR18	20250111_220533	1
CR19	20250113_140919	4
CR20	20250115_023750	2
CR21	20250115_233012	16
CR22	20250117_115259	83
CR23	20250117_185153	0
CR24	20250119_042307	166
CR25	20250121_225547	0
CR26	20250122_155158	321
CR27	20250125_025432	0
CR28	20250125_034440	50
CR29	20250128_153832	0
CR30	20250128_220319	0
CR31	20250131_065640	47
CR32	20250131_103628	40
CR33	20250203_125407	0
CR34	20250214_031401	3
CR35	20250215_063517	59
CR36	20250215_171431	0
CR37	20250219_010304	0
CR38	20250304_191440	123
CR39	20250311_231043	129